It isn't so much a matter of "What will other people want in my portfolio?" as one of "If a dozen people see something in a photo I don't see, perhaps I should pay some attention."
For example, in
this set of photos, I've gotten a fair amount of positive feedback from different people about
this shot. Personally, I don't think it's a very strong shot at all. It's not
bad, it's just not particularly great. If I were going through this set for an image to add to the portfolio short-list, I'd not give this shot a second thought. But apparently enough people see something in it that, in light of their feedback, I should at the very least give it some consideration.
This is more of what I'm referring to. It's one thing to have an eye for taking photos, it's another thing entirely for having an eye for picking the best photo out of a hundred. This is why news magazines have photo editors; they see the big picture (as it were). If
Life simpy ran whatever shots its photographers thought were their best, you'd have a big collection of random photos that have no real cohesive thematic element.