@Panda:
First of all, I want to say that I believe there are two basic types of complaints in regards to Robin's character. There are those who simply don't much care for her, or would simply like to see more active participation from her, which from your post seems to be the type you are; then, there are those that feel her character has actively gotten worse, and is being treated poorly by Oda (see the poster(s) that were calling her a walking pair of tits).
To be blunt, I feel the latter type is flat out wrong. Robin's character, from the moment she first joined the crew, has always been extremely subdued. You might argue that at first this was because she was simply using them like everyone else she ever had, and had not yet truly come to trust them, but even after Enies Lobby, her portrayal was much the same. A darkly humorous comment here, a smile and chuckle at the crew's antics there, the occasional hint at the mysteries of the Void Century every couple of arcs to keep us readers hooked on that.
Now, to speak more to you, if that sort of character simply doesn't interest you, or you would like to see more from her, then I can't really argue with that, since it comes down to personal taste. However, I do have to question your hypothetical changes to her role in this arc, specifically. You're hardly the first person I've seen with this sort of opinion; a number of posters seem to think that Robin should have been more involved in strategy and planning and such. To be quite frank, my reaction to that is simply one of wondering how the heck so many people got that interpretation of Robin's character.
To elaborate! Yes, Robin has always been one of the 'intelligent' Straw Hats, but the important thing here is to understand in what way. To me, at least, Robin's intelligence hsa always been in the sense of learning about and understanding the world around her, on a large scale. After all, her main character arc revolves around finding the Ponyglyphs and learning about the Void Century. With that in mind, I could understand thinking she should have pitched in with talk about the New World and taking on one of the Emperors, although honestly it doesn't seem like there was much she could have added that wasn't already covered.
What I don't get, and again, you aren't the only one that has brought it up, is this business with 'Robin the Strategist'; believing that she should have been jumping right in on the planning, or cased the lab within minutes of stepping inside, and that it was horribly out of character and a missed opportunity for her not to have. I simply have to ask: where are people seeing this as part of her character? Yes, she's 'intelligent', but that can mean many things, and as I've already said, I don't think her intelligence has ever really been much shown to be in that direction.
The best I can come up with, beyond simply assuming people are projecting what they would want her character to be like, is that they are inferring from her past on the run that she must have those sort of skills / inclinations. If that's where people are coming from, then I have two responses. First of all, I don't think she was ever shown as much of a strategist type even in her flashback. Yes, she evaded the government for all those years, but to me it came across as more a desperate life on the run, always barely one step ahead, than as any sort of carefully crafted plan. Secondly, even if you disagree with my first point, I would argue that the whole point of her coming to accept the Straw Hats was the trust that she would no longer have to live like that; that she had finally found people she could rely on, and trust to pull through for her, even without her having to take charge and plan things out.
To summarize, to me, given her forced past of having to depend always only upon herself, the relatively passive Robin we have, that finally can simply sit back a little and rely on others to work things out, makes far more sense than what frankly comes across to me as a sort of fan-fiction super-spy Robin that some people seem to wish we had.
P.S. Yes I know, another wall of text that nobody will care to read, but at least I managed to refrain from going off about Brook when someone made a comment about him!
Good post, and I agree completely. As well, I've always been under the impression she's been holding back so that the "kids" could have more fun.