I think it's because unlike what you said, that "It's as valid as it was last night", the vast majority of moaners are using the term as a short hand way of criticising the tactic. With many even going as far as suggesting -- as they often do on here -- that it's the "wrong" way of playing football, along with hints of the expected equation of, money in = expansive, free flowing football out.
How we set up last night was José Mourinho to a T. It's Chelsea's winning UCL campaign version 2.0. So for people to tune in, knowing how we are likely to set up, knowing we were missing our biggest attacking threats, knowing what Atletico were likely to produce, what exactly did they have in mind? What spectacle did they think they were about to take in?
As others on here correctly stated last night, too many modern football fans have no interest in the defensive side of the game. Defence seems to have become a dirty word. Unfortunately for those people, this is how tactics work, you do what you must to win. But you know it's bad when you have people saying...
Mourinho's Chelsea don't owe anybody a good show. The complaints are made even more ridiculous when you consider just how successful Chelsea have been in European competition in recent years. It's all well and good complaining about the manner in which we go about getting results, but at least we're there, in the mix. And any supporter who wants to pretend like they would have it any other way were they in semi-finals is either a liar or an idiot, maybe both. Because I'd rather be the rough looking Chelsea side possibly on our way to lifting our third European trophy in as many years than the gate keepers of beautiful football with precisely squat. Going out in style is still going out.
We could go in to the whole José hypocrisy bollocks too, but whatever, football manager, innit.
I think Martin Samuel summed it up quite nicely.