It's chickenshit. Plunking for the sake of payback is definitely chickenshit. As a matter of fact, that's cunt-face barrett chickenshit level.
On the other hand, inside pitches are part of the game. Does STL crowd the plate? They sure as hell do.
Big Deal. Sometimes it works, sometimes it doesn't. Houston does it too so it's hard to fault one team over another.
As to your other point, do the Astros stop and watch their homeruns? No, not usually. Is that a cardinal sin? I don't think so. I don't care for it but that's me. It does not merit a plunking. Crowding the plate, however, merits an inside pitch to push them off the plate. That's just smart pitching.