I think the most relevant reason to be careful here is in the paragraph right after the list of alternate things you can do with Wish. Emphasis mine:
You might be able to achieve something beyond the scope of the above examples. State your with to the DM as precisely as possible. The DM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong. This spell might simply fail, the efeect you desire might only be partly achieved, or you might suffer some unforeseen consequence as a result of how you worded the wish.
"So you wanted your intelligence to be 30, right? Great! Hmm... seeing as this list here doesn't include permanently increasing ability scores, I've decided to grant it with an 'unforeseen consequence'. You're now a sentient tome of magic. Since your new body doesn't have appendages at all, you can't cast spells with verbal or somatic components. Oh, lacking eyes and such will make it awfully hard to read your spell book and change your prepared spells...
"What's that? You want to amend it so you keep your own body? I am a generous and forgiving DM, so I suppose I'll allow that. Unfortunately, the spell has to cannibalize your own body to make (and make room for) that bigger brain of yours. Your skull is now much thinner, so you take an extra d6 of damage whenever you take damage. You can't move too quickly, either, for fear of smashing your oversized brain on that cramped skull. Oh, and we had to borrow some of those nerves from your hands, tongue, and muscles to make more brain matter. Your dexterity goes down 5 points, and you no longer have the fine dexterity needed for those verbal/somatic components..."
Overall, the game has some pretty hard caps on ability scores with the intent of keeping the balance with respect to high-level monsters. You literally risk everything your character (or the party, or the world) is/has to bend those rules.
Suffice to say that simply being unable to cast Wish ever again could well be the best thing to happen to you all day.