Personally, I find it is asinine to suggest shrugging off what the Astros are accused of because "stealing signs" has always been part of baseball. It should be investigated and if it's found that they have been using an elaborate camera system to steal signs from opposing teams they should be punished significantly for that. But yeah, I'm not in favor of forfeiting championships...
And I don't see how the steroid argument isn't incredibly apt:
Obviously there has been steady improvement in player diets and training since MLB began. And more importantly major development in health, fitness, nutrition and exercise in general. There is no question the average MLB player is significantly more maximized and optimized to produce stats than someone like Babe Ruth, who boozed and ate hot dogs on game nights.
Yet with HGH and other steroids, MLB and the public was able to decide on a certain limit to what an individual could legally do to improve his body under MLB rules.
Likewise, sign stealing and the gamesmanship around it, tipping pitches, etc. has always been a part of the game, and has no doubt seen significant advances over the last 100 years. But to suggest it wouldn't be utterly simple to specifically establish in the MLB rulebook a clear set of enforcable guidelines around sign-stealing... come on.
Clarify the rule. Establish strict punishment. Enforce.
If it ends up being found to have been truly egregious enough - put an asterisk on their championship.