I think another thing people face with Taijiquan is that it's a rare art. Or at least seems to be rare to me. Since it's been spoken of so often, as of late, I've noticed many "Kung-fu" schools slapping it on there name or sight.
I don't want to be mean...but it's going to sound bad... I'll also night point out any schools, because without actually going to them I have no place making a judgement. (not to mention the fact that I am not a pillar of martial arts excellence myself

)
I've found that many of the schools I see who teach "taijiquan" add it on as a "health exercise" to encourage those that can not handle a full and dynamic system. The issue being the teachers, teaching these methods, simply know the sequence of movements and do not themselves do taijiquan. So in many cases, I believe that most are not able to teach it as a combat art, since they dont' really "know" it. I don't think taijiquan is a single form for health on the sight but must be focused on. (After talking with many guys on here such as Xue Sheng refocusing on taijiquan has made a great difference for me)
Even in China (from what I understand) they have "taijiquan" breaks at work, simliar to "tea time" in England. People learn the moving meditation side.
I've studied Shaolin-Do's Taijiquan (and their other internal arts) for 5 years now, and I still suck compared to my sifu. I will say though that he has impressed me with his aptitude and understanding of Taijiquan. Over the years I've learned to sink my weight, move energy from my feet in an explosive manor (fajin, though beginner level) and develop what we call "listening skills". It has greatly improved my sparring and I love what I am learning. If you put me up against another I feel confident in my abilities now, and though I've made leaps and bounds from day one, my sifu will still toss me like I'm made of straw. I'm just over half his age and have probably 90lbs or so on him. However Sifu has been studying for 30 some years, and to obtain his level of ability will take me a great deal more study. My point is, schools that teach the combat applications, and fighting techniques of Taijiquan do exist. They are just few and far between it seems.
I am under the belief that this is because it takes a great deal of time before taijiquan becomes combat effective. This is at least my experience with it.
I've been to numerous other schools and styles. You go in and in the first month you'll be throwing attacks that can hurt other people. In a year I would say most can spar fairly well (this depends on the person and lessons). However with Taijiquan, the 5 years I've spent and I would say I'm at beginner to intermediate level regardless of my sash. Why?
Simply because, breathing and meditation, focus of mind and intent, cultivation, movement, rooting and uprooting all are an art in themselves. I feel it takes another direction then just throwing attacks and works with moving with your opponent to make there movements work against them.
The translation (as I understand it) is Tai Ji Quan = Grand Ultimate Fist
I think it's deserving of this name, but it doesn't become that way for the practitioner over night. I think one could practice for a life time and still improve with it every day. I know this applies to most things, however with taijiquan I find myself still looking and learning new things about the beginner stances and movements to this day :S