You do know priority tags don't do anything, right?

EasyJet is a pretty good airline. I'll fly on it quite happily but the bundle I get with BA tends to win, partly via status. The price is generally very competitive once things like seating choice is factored in.

Going through the list:

1) most passengers in Y don't check in, they use online or phone BPs, so no need for that many agents (and you got through in time). It's bad luck if you get a delay in the queue, but can happen on any airline.
2) priority tags - mostly for frequent flier comedy and traveler ego as mentioned. You delayed the queue by insisting on them.
3) fast track - nice when you get it, you don't always, it's never caused me much delay. Often you can pay a fiver and get it on any airline but I never bother.
4/5) There was a lounge available, you just didn't go there. I always check with flight radar the status of the incoming flight I'm on, when it lands there is at least 20-30 minutes to the earliest boarding. EasyJet will sometimes line you up well in advance of the plane landing incidentally.
6) TXL issue.
7) And so what? Bus gates are used everywhere. I was on one yesterday in Doha. I'd be amazed if easyjet wasn't the same.