Are we talking about american kickboxers here? If so, then yes, no low kicks, but almost everyone practices low kicks nowadays. Even knees, to a lesser extent.
One thing i know, is that the Thai roundhouse has pretty much become the gold standard when it comes to most kickboxing matches.
Currently, kickboxing is just kickboxing (muay thai included), what is more important are the rules you are training for, THAT is what determines your style of fighting more than anything.
a good example would be Lucien Carbin's Gym (the trainer of Alistair Overeem, and Tyrone Spong-ftw-), he just considers himself kickboxing, sometime Thai boxing even though there is clinching and knees. shit is interchangeable bro.
http://www.youtube.com/watch?v=NgrDz1BSMbM
that being said. i don't think i'm gonna talk about this anymore because i keep mixing myself up. But seriously, modern day Kickboxing really resembles muay thai, just without the clinching and elbows, and with deeper boxing skill.