Hiya!
[MENTION=61277]Mepher[/MENTION] pretty much nails it for me.
Different game systems (and even editions) have their own "feeling". Me? I'm a BECMI or 1e/HM4 guy. We played (still play often enough) 5e since the Starter Box. It's definitely got a better feeling than 2.x through Pathfinder, but it just has too many...hmm... "expectations of heroically epic PC's"? In that I mean with 1e/HM4 or BECMI, you make a PC. Everyone forms a party. Everyone decides, usually by vote, on what to do, where to go, etc. The PC's are just barely above commoners, overall, in survivability. What PC's have is the ability to actually gain levels (and in some cases, even have a Class to begin with). How "heroic" and what "heroics" to undertake is up to them. There is no expectation in 1e or Hackmaster that a PC will 'eventually get to 10th, 20th or 36th level'. In fact, quite the opposite; expectation of death is the norm.
With 5e, that's not the case. With 5e it is expected that a PC will gain levels and eventually get to 20th level...simply in the way that character class special abilities are spaced out for 20 levels. As others have said, Basic, 1e, 2e are all "Front Loaded" for Classes; you get most of your stuff in the first three levels, maybe one or two more by the time you hit 7th or so, and perhaps one more ability with 'oomph' at 9th or thereabouts. Some classes, the more "unusual" ones, had more spread out abilities (at least in 1e/HM), like Monk or Assassin...but those were pretty rare classes for a PC (remember, in 1e/HM you had class Prerequisites for your stats...and some of the rare classes needed really high numbers...even hard to get when you use the default 3d6 in order!).
As for "if you like 5e, no point in learning another", I find this perplexing. It's like saying "if you like vanilla ice cream, no point in trying any other flavour". Variety is the spice of life...and this goes for RPG systems and editions too.
^_^
Paul L. Ming