You're falling for the Left's attempt to redefine judicial activism. Overturning a past bad, constitutionally-unfounded decision like Roe is not activism at all. Doing away with an activist decision is not activism. It could only be honestly called activism if after overturning Roe, the justices then issed an edict banning abortions. But of course there is no thought that they would do that. Instead they would simply return the matter to where it belongs -- the states -- and would not mandate any outcome.
And don't fall for this nonsense about the importance of precedent. The pre-Roberts Sup Court had no such regard for precedent when it struck down state sodomy laws in Lawrence vs Texas, after upholding them less than 20 yrs earlier back in the late 80s. They had no regard for precedent when they struck down captial punishment for teenage minors, again, after having upheld it back in the 80s. In both of these cases, the law was 'settled' until the Sup Court decided they didn't like it.
So clearly, precedent only matters to this Sup Court when it protects a liberal decision, otherwise it should be tossed aside in favor of the changing values of society...as divined by the Sup Court.
And you are correct in that there is much speculation that Roberts will be some new type of SCOTUS judge, i.e. one who will be reluctant to overturn precedent, such as with Roe, but who will refrain from voting in favor of similarly absurd, unconstitutional decisions on other matters; or to put it another way, who would not support setting bad precedent on future issues, like say, gay marriage. In short, he would accep the damage that has been done, but would not contribute to future activism.
If this is truly Roberts, then he would be unique, because generally a pro-Roe judge is terrible on most other social/cultural issues. And that gets to your point about there being too much focus on Roe. You're right that it isn't the only important question, but it goes to a general question of judicial philosophy. You can find decisions by pro-Roe O'Connor and Kennedy where they didn't side with the Left on a social issues (the Boy Scouts case is the last one I can think of where the conservatives won), but generally, they seem to have become more liberal on these issues over time. Obviously, support for Roe doesn't denote support for other liberal positions, but a person inclined to support Roe is simply more likely to be of a mindset that supports similar activism on other issues. Do you doubt that O'Connor and Kennedy would vote to impose gay marriage/civil unions?
So if Roberts does prove this speculation correct, then he'd be unique, but my guess is that he will end up on side or the other; the originalist/restrained block with Scalia and Thomas, or the activist wing of the rest.
But if I'm wrong, then while I'd still prefer another Scalia, I would still be relieved if he were to help restrain the Court on future cases.