Well that would be incorrect since I'd upgrade to a 4 from my 3mk1 (I'm prob not the only one). And why would it matter to those who don't want / need to upgrade? - stick with what u have, no-one will be twisting any arms.
Capacity for one - I can easily red line cpu in my 3-mk1 with a not so kitchen sinky preset. There's also a hefty list of next gen wishes
here.
(I'm sure someone will say "just upgrade to a 3T" to which I would answer that I find the best value for myself has been to upgrade to major gen changes (I purchased Ultra in 2009, II in 2012, 3mk1 in 2018).