Because it's a cramped space.
People who get up when the plane touches ground are going to be standing in the walkway with their bags and butts pressed against other people for all the time it takes for the plane to taxi in and connect the doors to the terminal or stairs.
They do not get out faster.
Being ready to go means faster by definition and also how is anyone in the aisle's butt pressed against people in middle and window seats? That doesn't make any sense
Ps. you're not allowed to stand while taxiing is occurring.
Vote with your wallet (wherever possible)
It's not complicated. You just said you're in no hurry. Unless you have a window seat, you couldn't possibly not be slowing others down.
I've travelled for work all my life, I've flied idk, hundreds of times, my luggage got lost exactly one time, when I got a connection in Switzerland, they left it on the tarmac. Luckily it was my toolbox, not my personal bag.
Another time my luggage lost me, meaning they loaded it on an earlier flight and then cancelled mine, so my luggage got to destination and I didn't. That was on a flight from Miami to New York.
I’ve had my luggage lost twice, and they don’t pay you back for that.
Excuse me?
Are you making assumptions or do you have stats on this?
If they managed where luggage was stored in the overhead, they could reduce it 10 fold. The whole wait is because people need to go back x rows past people standing to get their luggage. Even if they made everyone sit and deboard in zones it could be way faster.
If you did you would've shared them.
The other consideration it has is on net luggage weight. Yeah, they're still checking bags for "free" but they're smaller and lighter - saving fuel by increasing efficiency. And that's also a good thing from a pollution point!
Where's Chapter 2? 
Best ones are those who can't actually get to the aisle so they're standing with their heads ducked under the overhead compartments.
It's not the people who are chill and out of the way, it's the 80 year old dude who forces his way in front of you, who is totally not ready to get moving, looking for his stuff while in the aisle, can't get his luggage down by himself and walks slower than hell.
It's this. Stay the fuck down until your row is clearing.
I'm betting on the money. If you think the airlines haven't looked at whether it would be more expedient and therefore profitable to organize deplaning or leave things to animal instincts you are underestimating their greed.
Did you ask the hotel? If you are nice they might wash it for free
Vote with your wallet (wherever possible)
The last large airline to NOT charge for checked bags in the USA, Southwest airlines, has switched to charging for bags.
Oddly the ones that have the best outcome for the deplaning scenario from this bad situation of paid checked bags are the ones that also charge for carry ons like Spirit or Frontier in the USA. So there is an incentive to NOT bring a carry on because you'll be charged for it and instead just pay to check a bag (which has more capacity).
Not GP, but I get free checked bags with “priority” (so they show up first) and pretty much only check a bag. Sometimes I just check a small carryon item.
I carry a backpack with my laptop and other electronics on the plane and that’s it.
Dude why do you think the airlines are in a hurry? Lol
Everything they do is slow and behind schedule. They do not care, they already have your money. It doesn't save them anything to deboard a couple minutes faster.
Edit: I could probably list several things they could do to for sure save time but they don't do because again, they already have your money
