I think, first of all, obviously some ITM players tongue and do it just great, so, do what you like. I don’t tongue… if I need my mouth to stop the wind, or force the start of a jump into the upper octave, I use a glottal-stop.
I think, more and more, that the ‘not tonguing’ comes from both overtonguing, so people are told not to and decide this means ‘never tongue’, and from flute-playing, though I suspect that somewhere out there there are ITM players who tongue on the flute too…
My reasons for not tonguing,other than being told it ‘wasn’t traditional’ are that, once I stopped tonguing I was forced to learn my cuts and taps, and once I did, I discovered they were -way- faster than tonguing… I can’t imagine double-tonguing or triple-tonguing fast enough to replace a roll, though you could (as Brother Steve does) supplement a roll with tonguing.
Thinking on it, I think if I did reintroduce tonguing into my playing, I’d not use it for articulation of like-notes-together but for emphasis of on-beat notes. I like the sound of a crisp cut for most articulations. (Not that most of my cuts -are- crisp, but hey, you have to start somewhere…
)
I do think it’s very important to be -able- to play without tonguing, that is, your fingers should be capable of articulating and ornamenting everything, just because that much speed and dexterity is good for playing well, but I think you using tonguing… in a restrained way… is just fine, too, as long as you aren’t using it as a crutch to cover finger weakness…
That is, you should figure out what sounds best, and get good enough to do -that-, and not tongue because you can’t get your cuts crisp enough or start the upper octave without it.
So says opinionated me, with still less than a year of whistling, but I’m getting close. 
–Chris