I care about doctrine because it helps me know the Lord. Not a Jesus fashioned as I think he should be, or one who adapts himself to current culture, though believing in such a compliant and flexible Jesus appeals to me. Truthfully, I wouldn't mind tweaking the Bible here and there, making it just a little more comfortable, nor would I object to receiving extra-biblical revelations. But Scripture, studied in context and with a dependence on the Holy Spirit leads me to see Jesus as He actually is.
Do I claim to know Him perfectly? No. In fact, I have only begun understanding the great doctrines of the Christian faith, partly because I spent years in Christian groups that emphasized experiential spirituality, partly because the days before the Internet made study materials less accessible to me (due to my disability and my finances), and mostly because I didn't mind "going with the flow" of whatever my church went after at any given season.
Following the crowd and swallowing the Kool-Aid proved easier than learning to distinguish good doctrine from bad. Also, the non-resistance ensured my acceptance with peers and those in leadership. Sadly, it also demonstrated that I worshiped my church more than I worshiped the Lord.
Now, as I read and study the Bible in context (rather than scanning through it until something gave me spiritual goose bumps), the Lord reveals Himself. I watch His holiness in dealing with Israel, and His humility during His Incarnation. Currently, He confronts my sinful behaviors as I read Proverbs, and assures me in Hebrews that He intercedes on my behalf as the eternal High Priest. The doctrine of human depravity keeps me dependent on Him, and the doctrine of His sovereignty strengthens my trust in Him. Scripture's great doctrines show me His perspectives on relationships, sin, faith, money and just about everything else in life.
Most importantly, Scripture teaches me (for the word "doctrine" means nothing more than "teaching") of Christ's preeminence in all creation. He is not a god who suits himself to my fancy. Quite the contrary, He is the holy yet gracious King Who allows me the privilege of serving Him for all eternity. The doctrines of the Bible display His majesty, drawing me to praise and worship Him in thrilled anticipation of being physically in His glorious presence.