Wresting With The Word: Eagerly Desiring The Greater Gifts

In 1 Corinthians 12:31, Paul tells us to "eagerly desire the greater gifts." But only a few verses prior Paul explains that it is the Spirit who gives us our spiritual gifts, "just as He determines" (12:11). How do I reconcile these two thoughts? How can I desire the "greater gifts" if their distribution is outside of my control?

In verse 15 Paul says, "If the foot should say, 'Because I am not a hand, I do not belong to the body,' it would not for that reason cease to be part of the body." In the proceeding verses (up until verse 27), Paul goes on to explain how no gifts, or "parts," are any less or more significant than the others. Each part is vital to the body as a whole: "The eye cannot say to the hand, 'I don't need you!' And the head cannot say to the feet, 'I don't need you!'" (12:21). There seems to be an equalizing affect that each part plays in respect to the all the other individual parts, and it is what equalizes the body as a whole.

Then, in verse 28, Paul seems to rank some of the roles in accordance with God's appointing, seemingly establishing this system of "greater" gifts.

But again, if the distribution of our spiritual gifts is carried out by the Spirit's divine will, why would we desire the greater ones, instead of merely accepting what He has portioned us with humility and thankfulness? I understand this verse is probably speaking in anticipation of the actual distribution, but I feel like we're setting ourselves up to fail if we desiring gifts A, B, or C, instead of waiting in humble expectation.

One commentary said, "but this does not prevent men earnestly seeking, by prayer and watchfulness... the [greater] gifts." I agree that it is good to desire the things of God--His holiness, righteousness and His will--but what good does this do if we ultimately have no control over what gifts we receive? Doesn't this just leave room for failed expectations?

If we are told to desire the greater gifts, I feel like this is only going to create feelings of discontentment, jealousy and frustration. "Desire apostleship! Desire prophecy! For these are the greater gifts, the ones worth desiring!" (Or pick your gift of choice.) But what if what we desire isn't what we receive? Won't we despise what the Spirit has given us and therefore wrongly covet (King James: "covet earnestly...") the greater gifts? I feel like this runs contrary to Paul's previous explanation of each part being significant to the whole. If that is true, why are there are parts which carry more weight than others, parts that are "greater"?

I don't believe that Paul is contradicting himself. I believe that the Word is God-breathed and God is perfect and His truth is infallible. But I just don't get what I'm being told to do in this last verse.