Regarding older games, I'm not a fan of automoive clear at all. It does certainly change the way a game plays. Although some prefer that "feel" you get on a auto-cleared EM, it certainly doesn't play how the company/designer ever play tested it back in the day. Knowing this, the shots, saucers, slings, spinners, scoops, ect. are ALL going to play different, since the speed and flow of the ball has now been "modified".
Additionally, where were you ever going to play a game on location back in the 60's/70's with a clear coated play field? I would much rather play those vintage pinball games the was they existed on location, in the era of when they were manufactured. Adding things like LEDs and automotive clear certainly changes them in a way that differs from how they ever previsouly existed.
Bad or good? That's an opinion. But it certainly does change the game. That is certain.