1.) Yes, I agree, and I don't know what the specific worst issue is as I think it may be a combination of these things compounding the issue with crowding. This was only an issue for us in the Magic Kingdom and only in the morning. Epcot did have long bag check lines at park open some days, but when I say "long" I mean "15 minutes" not an hour. MK bag check in the evening was no problem. We had no problems at Animal Kingdom, and I skipped the studios last time so I have no insight.
1a.) Another thing that's super annoying is that they've taken many of the parking spaces "close enough to walk" (comfortably, I recognize you could walk from Florida to California, but I mean a reasonably fit and energetic person would elect to walk rather than wait on a tram) and designated them for "premium parking". This is the recent change that irks me the most. I don't want to ride a tram. I want to get there before the park opens and get a close space!
And I don't want to pay an extra $15 for it!!!
2.) Absolutely! If you can get away with not having a bag I would for sure go without. However, if you have a stroller/
scooter pouch/wristlet etc. those items are considered bags and you will have to wait along with everyone else. Just beware - we were trying to leave the MK at about 10:15 or 10:30 (when the masses are crowding in) and the "lines" of people coming from the Ferry to the bag check stations on the right side of the park entrance were 100% solid, think WALL of people as far as the eye could see. We wanted to get on the resort launch boat back to Poly but based on where we were siphoned through the exit and since we literally could not get through the crowd of people we walked to contemporary and took the monorail. All this to say that even going bagless, you may still be one fish in a huge stream and gridlocked for a while regardless of your wisdom in not carrying a bag.
Now... who can convince my family that they won't end up needing Advil, bandaids, flip flops, more sunscreen, ponchos, and all the other crap I am designated to carry around in my parks bag?