An "opinion" on Ditra? Well most of the respondents here do tiling of some sort for a living, where you trade your reputation as a professional for other people's hard earned cash, to feed themselves and their family and create wealth by growing their business - and most of them know and use Ditra. Not everywhere, but it is a major component of one or two of the half-a-dozen standardised methods of tiling a floor.
Do you need it? No, but if you know your tiling, then it suggests itself more and more often on many projects for specific purposes. Put it this way: it is an advancement to the tiling industry as a whole. Therefore, it has undergone severe scrutiny, has been tested, tried and adopted by other professionals in the trade. Some say, it is a standard unto itself.
An "uncoupling membrane" reduces the liklihood of cracking in floors; cracks have a nasty way of diminishing the reputation of the tilesetter and therefore the cost of such a product is often outweighed by the advantages to the flooring system, to the homeowner and to the installer. And 'cost' shouldn't be evaluated strictly on a 'per sq ft' basis as many people tend to do and, again, the people who see the larger picture will say the cost is negligible compared to the costs of replacement or re-do...
Yours is a fair question; I don't think your method of collecting information was anything near a scientific study that would have allowed you to make an informed decision on it - but if you do indeeed take your sampling material from TV shows, how is it that you didn't consult 'Holmes on Homes' (arguably the largest renovation show currently on the air)? or 'This Old House'?:huh:
So be careful by putting forth the hypothesis that "people don't use it"...look at your sample first, then ask if you're looking in the right place.:laughing: