Excellent post.
I've been brewing for around 6 years now. I'm only just now starting to collect the gear to go to all grain.
In my 6 years of extract brewing I've made some outstanding beers (I'd put them alongside the stuff I pay $15 for a 4-pack for at the store), and I've made some beers that, while I've never dumped a batch, I was a bit relieved when they were finally gone.
I'll be set up to do all grain soon. I fully expect that I'll make some absolutely outstanding AG beers. I also fully expect that I'll make some really crappy AG beers.
I'm finally investing in AG gear for the greater control. Along with that comes opportunity to experiment. With experimentation comes unexpected results sometimes. It's all part of the fun and what makes homebrewing an enjoyable hobby. If all I wanted was great beer, every time, then I could stop by the local brewpubs and get some growlers filled every night on the way home from work for much less than what I've spent on my brewing hobby.
Also, I fully expect to continue doing extract batches from time to time for as long as I continue to brew. Some beers just don't need to be done AG. Some days I won't have time for an AG brew session but will still want to keep the pipeline going. And some days the weather will just be too cold and nasty to have an outdoor brew session. While I'm in the process of accumulating AG equipment, there will be a period of time in there when I have the gear to do 10 gallon extract batches, but am missing a piece or two to go AG. I'll probably do some 10 gallon extract batches during that time.
I expect going to AG to open up some options for me. But it took me 6 years of brewing extract to fully appreciate what those new options will be. I'm also going to have a lot of new things to learn, and for me learning new things is at the top of the list of what makes this hobby fun.
I'm glad I waited.