I agree that it's important yo know sq footage/meterage when house hunting....having a floorplan is really essential imho as I like to plan where we'll site our masses of furniture.
In the past I've also used spreadsheets to compare criteria of potential purchases and overall size has been one of the most important factors for me.
I guess we were spoiled because we were extremely fortunate to buy a 3500 sq ft Victorian house a few years back, which had humungous rooms and that has always been the benchmark by which we've measured future purchases!
We're not fans of new builds anyway as our style is traditional Arts & Crafts, but even if we were, we would be discouraged by the overall lack of space many new build rooms provide - I'd rather less rooms but larger ones if I had to choose.....
Our current house was a downsize for us at 2000 sq ft, compared to the one we just sold (2500) and for DH and me that's about as small as we'd want to go - we run a business from home and have two bouncy dogs, plus we like our own space for chilling out and despite a cull we still have six sofas so many of the properties we viewed on RM were ruled out as being way too tiny for our stuff us.
Mind you, I'm a firm believer in playing around with rooms and not necessarily using them for the purpose they were intended - for example we've opted to use the master bedroom here as an upstairs 'snug' because it has great views from a cosy window seat - perfect TV room material!
I wish they'd also include garden measurements - our last house had 1/3 acre but we had no idea of this till we turned up to view - if we'd listened to the EA we might never have viewed this house as the EA told us on the phone the garden was small, when it's actually in excess of 100' x 60' which for this area is fairly large......