dtgreene: The problem with such a low cap is that it means that level ups are rather infrequent, and much of the fun of RPGs for me is seeing character growth; it's just not satisfying when you can go a whole session without any growth.
This sort of reason is why I prefer systems where stats/skills improve through usage, or failing that, games with frequent leveling and a high level cap (and less power increase per level up, to keep things under control). Or, incremental games, which are all about increasing numbers.
Incidentally, an alternative to the high power of 3e epic levels would be to softcap power at level 20. Make it so that you gain significantly less at level up past a certain point. One can see this, for example, in Dragon Quest 3, where past level 45 or so you don't gain much in terms of stats at level up (and you probably know all the spells by that point).
(With that said, I think the D&D to-hit mechanic, and the fact that things like level and armor affect hit chance rather than damage, is part of the reason D&D doesn't scale so well.)
ArthurWalden: Hmm...is that why some D&D players say they prefer low level characters? Keep in mind, though, there are a near infinite variety of types of role players out there.
I think it may actually be largely due to the nature of some of the high-level spells, spells that might eliminate certain types of challenges that low-level adventurers might face. (Fly and Teleport are examples here.)
Also, with all the options, either:
* Combat tends to take longer
* In some games (though I don't know if this is the case for any D&D version), the reverse can happen, where everything becomes a glass cannon
The issue with to-hit modifiers is certainly a reason, but my impression is that, in 5e, it's been reduced, as your level has far less of an impact there than it did in earlier editions. (I'm still of the opinion that armor should give damage reduction rather than chance to evade; it makes more sense and doesn't have the same scaling issue that AC does, assuming that damage can keep up with armor damage reduction.)
Thing is, as numbers get bigger, things can get harder to balance.
(Incidentally, the issue of balancing big numbers comes up in incremental games. While there's generally no "opponent" to worry about (so you don't have things like to-hit or damage), there's still the issue of inflation (one reason why softcaps are common), as well as the fact that, once numbers get *really* big (as in, too big for scientific notation), they no longer behave like smaller numbers, as even multiplication eventually stops being useful.)