I could see how the tethering issue could happen. Leica has no headspace for the studio (or roll-your-own-studio location shoot) world and their only DSLR-esque body to date has been the sghort-lived, low-production DMR, which if IIRC (and I could be wrong) had no tethering ability. I shot with one very briefly but can't recall about tethering.
Now, that said, some simple benchmarking and some of that supposed in-depth input from studio/fashion shooters (or a latte at any decent studio) during the design of the system would have nailed that down in a hurry. "..yup, make sure it's FW800, large buffer and quick tethered preview.." it's like saying it should have a hand strap - pretty well a given.
Shame, as they could have dumped a huge buffer in the beast (RAM is dirt cheap), tweaked some nice software and made the buffer and tethering speed a cheap-to-implement but very notable selling point vs the competition. But instead, they cripple it AND make you use a (I assume) spendy and what will be hard to find custom cable that can lock on to the camera - thus sending it flying with the first errant foot. I guess at that point, finding a replacement cable won't be your biggest concern anyway. Tethering isn't for everyone as was said, but you need to have that ability, in a decent form, onboard. It's a cheap way to avoid excluding LOTs of potential customers
All that being what it is, the S2 may be publicly targeted at the pro studio/fashion market, but as others have said, that's NOT where the VAST bulk of the unit's initial sales will come from. The trick will be what will happen after that initial bubble of sales to die-hard Leicaphiles and the odd bleeding-edge user. If cash is slow to come in, the product line growth might slow which will slow sales even more as folks get nervous about orphaning, and round and round we go.
The S2 is a nice idea, looks pretty good but has some notable shortcomings. However, to be fair, it is the firm's first MFDB body and could be refined handily in an S3, but the product line, Leica's rep in that target market and the company itself need to make it to an S3 stage to be able to improve upon the concept.
As for the "if you don't want it, don't buy it ..." comments, a big issue that raises hackles is the firm and it's die-hard fan's praising the thing (well prior to release let alone afterwards), like Leica's first step into MFDB land and back into DSLRs in general was the panacea to everyone's issues with MFDBs/high-end SLRs or that it somehow 're-defines' photography. It's a interesting tweener body concept that has exploited some past lessons of other manufactures, but neglected to exploit some it should have. It looks great, has Nth percentile glass and from all accounts handles (note handles, not necessarily performs) well.
If some folks like it enough to buy, great, if many (who could afford to) don't, Leica shouldn't have any illusions as to why not. The S2 is a good first start. Lets see where (or IF) it goes from here.