I think a lot of this all comes down to the older ones of us - that includes me btw - remembering the thundering fullsome sounds we had on stage with the bigger gear, then not getting that with the smaller gear. But, as said, with the bass going FOH, and with monitoring being better than ever, do we need that thunder on stage? In reality, no, and the smaller gear is plenty loud enough for all of us I`m sure. But we just want that thunder! I did a gig last Sat where the monitoring was so good I wouldn`t have even needed the amp, I could have gone from my Sansamp straight to FOH.
Re lighter, smaller cabs, I had two Barefaced Super 12Ts and the pair together were easily equal to the 810 stacks that are provided at festivals. I then very stoopidly sold them! Happy with my Ashdown gear though, whilst not quite as light as the Barefaced I get the sound I want from some very robust cabs and as bought second hand, at a very reasonable outlay.