Seeing what each player had left in their deck could be interesting. You could take it a step further and have some type of post game report built into the game. Showing what was played per round, complete decks, etc. It wouldn't be a priority to do this but I don't see the harm in tossing it out there.
Allowing players to back out of games without playing them is going to be problematic. It may seem reasonable to let players duck out of bad match ups but it's unwise to assume it will be the only result of such a change. If everyone decides they're unwilling to play against any match up where they don't have an advantage you're going to have a problem. Games are going to be hard to find
.
The deck building implications are also of concern. Instead of building toward balance so you can handle most match ups people will build toward countering a handful and ducking out of everything else. Not good.
It could work with heavy restrictions on it. Some type of limit on the number of games you can consecutively bail on would be in order. Perhaps with a time-out period following dropping from a game, where you can't do it again until it expires. It's still probably not a great concept because it will add unnecessary overhead to the time it takes to find and play a game.
I'm not sure what you're asking for with the dialog suggestion. I could understand dialog to indicate you're still considering your next move, you need to hit the bathroom, you know you've lost and are conceding early, etc. Telling other players to shut up or otherwise being offensive toward them isn't going to improve anything though. Anything along those lines is out of place, IMO.