Rock and roll speakers?

Unsound....no one made the claim you are making. "Now back to our regularly scheduled program". ;?)

And, seemingly, there's no point not worth missing.

Yep size still matters when it comes to full range speaker output capacity, which is the main factor to consider to be able to play all kinds of music. If it can play the big stuff loud and well it can play all the rest. I think that was atmasphere's point that I agree with.

However, technology has evolved to enable somewhat more output from smaller speakers as well since that is what most people want. Although more of the same can only be better. Its all a question of how much you need. After that the rest is mostly what flavor you prefer. Most people prefer vanilla.

I think a critical element is the room, especially size, in which you plan to rock out.

If your speakers overdrive the room, the sound will likely be at best, unpleasant. And at worst, unlistenable.

I agree with most that dynamic range and ultimate volume levels might be the biggest concern. Though as has been already pointed out, often times (though not always) proper amplification can go a long way in negating that concern. Another issue is frequency response, and whether the room can handle it. Yet another issue is how well a given loudspeaker can present a satisfying soundstage and imaging. Now this last item might be more of an issue to those that listen to music that is recorded in such a manner as to preserve it, and less so if the music is not recorded with much concern for these matters. IME, classical music is more often likely to be in first category and pop music more likely to be in the second category.