One the of things about Biotest is they generally don't put out products which already saturate the market. The exception being Biotest Creatine, which I believe they decided to offer based on demand and the fact that we could be sure of its high quality and low price.
BCAA powder, however, seems to be covered by Superior Nutraceuticals in terms of quality and lowest price (I'm actually paraphrasing Biotest's own Bill Roberts here) so Biotest made the next best thing: super concentrated, affordable pills.
I'm not so sure Glutamine is so highly recommended here other than in very specific circumstances; i.e. use for glycogen replenishment during very low carb diets. It seems the general consensus with Biotest is to offer more novel compounds of a higher purity and concentration, usually at an earlier time, than anywhere else.
One thing you have to consider is the universality of products; weighing the options as to what type of product is going to benefit most of the people most of the time.
But if Biotest DID make an extremely low-carb Surge that tasted good...well, that would be one hell of a feat. Hydrolyzed whey and Glutamine and Glycine with BCAAs without carbs? vomits profusely