The point wasn't one of taste but relevancy.
It depends on what plane you are measuring relevancy in.
I have no doubt that when you are talking about the totality of the radio entertainment medium Howard is very relevant, if only based on revenue upstream generated.
Would he be relevant if one were discussing modern medicine? I don't think so.
Another, more appropriate, example: While I am sure Howard's audience size is comparable to Leno's or Letterman's [maybe it is even bigger, as you suggest], and certainly bigger than Jon Stewarts', I would wager that any of the latter three have a bigger impact on daily political views than Stern. So in the plane of relevancy regarding the impact on the political vox populi any of them would be more relevant than Stern [with the noted singular exception of one gubernatorial election and perhaps a senatorial one in NY state quite some time ago].
The point is, there is a small slice of life where certain entertainers are going to be relevant. Howard is quite relevant in one specific plane; ergo he is the proverbial big fish in a very small pond.