I don't think the discussion is 'if it works, does it matter how we get results?', I think it's more 'will we keep getting these results, if we play this way for the rest of the season?', and the answer is almost certainly not (in my view, and according to Xg).
Please don't misunderstand, the results have been fantastic, Carlo's done a great job of adapting the squad to a more limited style in a difficult period, and we're in a great position.
But this isn't how Carlo Ancelotti envisages his teams playing football longterm, and when we get the injured players back I imagine we'll be looking to play closer to the early part of the season than this current period.
As people have said, it's about balance and tradeoffs. If we look to play more expansively generally, we will concede more chances on our goal inevitably.