Hello KingJimmy, this is a good observation. I'm glad you are going to Reformed sources to learn about their views.
Speaking as a Reformed person, at least soteriologically, I will suggest immediately that Sproul may not be an adequate representative of the entire Reformed tradition. Sproul's views should be balanced with those of other Calvinist (I prefer "Pauline", but even Paul said He got his doctrine from Christ, so we're back to being "Christian") believers.
As an observation, every generation of believers is tempted to over react against whatever cultural swings seem most dangerous. Today, when Reformed believers find themselves occupying a tiny wing of the gargantuan professing Church, it should not surprise us if such affect is given to declaring their chief differences in doctrine. Looking outside of their polemical defenses, we will likely find more accurate presentations of their values.
Before showing some pertinent quotes, I will suggest perusing works by Joseph Alleine, Spurgeon, Whitefield, Sibbes, Luther, John Newton, to see how radiantly each emphasizes faith, though that emphasis is always subordinate to its object, Christ. In more recent times, consider Paul Washer (who first exposed my lack of genuine faith) or John Piper (who reminded me not to place faith in my faith, but in the finished work of Christ for everyone who will believe) or Rolfe Barnard, etc.
Here is a series of Paul Washer sermons, entitled "It comes down to Faith."
[url=http://www.sermonaudio.com/search.asp?sourceonly=true&currSection=sermonssource&keyword=gcc&subsetcat=series&subsetitem=By+Faith]It comes down to Faith[/url]
Here are some quotes by various Reformed brothers on the subject of faith, and may God bless you through them...
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Our heavenly king is pleased with all our graces: hot zeal and cool patience pleaseth Him; cheerful thankfulness and weeping repentance pleaseth Him; but none of them are welcome to Him without faith, as nothing can please Him without Christ.
-Thomas Adams
Other graces make us like Christ, faith makes us members of Christ.
-Thomas Watson
All other graces like birds in a nest depend upon what faih brings in to them.
-John Flavel
Faith is the captain grace.
-William Gurnall
The soul is the life of the body, Faith is the life of the soul. Christ is the life of faith.
-John Flavel
Till men have faith in Christ, their best services are but glorious sins.
-Thomas Brooks
Where reason cannot wade there faith may swim.
-Thomas Watson
We must understand that faith does not justify and save us by itself. . . but as an instrument, whereby we lay hold of and apply to ourselves Christ with His righteousness and merits, by which only we appear just before God. A small and weak hand, if it be able to reach the meat up to the mouth, as well performs its duty for the nourishment of the body as one of greater strength, because it is not the strength of the hand but the goodness of the meat which nourishes the body.
-George Downame
Faith is seated in the understanding, as well as in the will. It has an eye to see Christ, as well as a wing to fly to Him.
-Thomas Watson
Faith, hough it hath sometimes a trembling hand, it must not have a withered hand, but must stretch.
-Thomas Watson
Judas knew the scriptures and without doubt did assent to them, when he was so zealous a preacher of the gospel; but he never had so much as one drachma of justifying faith in his soul. . . Yea, Judas' master, the devil himself, is one far enough (I suppose) from justifying faith, yet he assents to the truth of the Word. . . Assent to the truth is but an act of the understanding, which reprobates and devils may exercise. But justifying faith is a compounded habit, and hath its seat both in the understanding and will: and, therefore, called a "believing with the heart" (Rom 10:10) yea, a "believing with all the heart." (Acts 8:37)
-William Gurnall
It is the office of faith to believe what we do not see, and it shall be the reward of faith to see what we do believe.
-Thomas Adams
Faith is your spiritual optic.
-Elisha Coles
It is the nature of faith to believe God upon His bare word. . . 'it will not be', saith sense; 'it cannot be', saith reason; 'it both can and will be,' saith faith, 'for I have a promise for it.'
-John Trapp.
If faith were assurance, then a man's sins would be pardoned before he believes, for he must necessarily be pardoned before he can know that he is pardoned. The candle must be lighted before I can see it is lighted. The child must be born before I can be assured it is born. The object of faith must be before the act. Assurance is rather the fruit of faith, than faith itself. It is in faith as the flower is in the root; faith in time, after much communion with God, acquaintance with the Word, and experience of His dealing with the soul, may flourish into assurance. But as the root truly lives before the flower appears, and continues when that hath shed its beautiful leaves, and is gone again: so doth true justifying faith live before assurance comes and after it disappears.
-William Gurnall
Faith is not assurance. If it were, Saint John might have speared his pains, who wrote "to them that believe on the name of the Son of god, that they might know that they have eternal life." They might then have said, "We do this already."
-William Gurnall
How weak soever the believer finds himself, and how powerful soever he perceives his enemy to be, it is all one to him, he hath no more to do but to put faith on work, and to wait till God works.
-David Dickson
Finally, if I may answer your question, "why [does] the Reformed theologian even sees faith as a necessary step in the ordo salutis. Why justification by faith, and not simply justification by mere irresistible election? Why the faith element altogether?"
Amongst myriad excellent answers, God uses faith as a means of bestowing His determined gifts simply because He is pleased to make foolish things the method of His wisdom.