Yes and no. In terms of personal power, ranged basic attacks are, as you say, just not that important.
But the fact that many ranged attackers don't have RBAs -is- really significant on a network effect level. It makes warlords and other leaders that take powers giving out rbas particularly weak, which means people don't take those classes in environments other than "we're all making up an optimized party together" -- which means that, in turn, ranged attackers who spend resources on having rbas are usually just wasting those resources. It's a bad situation all around.
Thought no list of ranged attackers with good rbas is complete without mentioning, you know, rogues -- with a great to-hit, and if they mis with the attack on their turn, amazing damage. (and rogues, like rangers, will pump static damage as they can, since while they don't attack twice, they do tend to hit).