Well, my rationale is, first of all, why would someone want to get a system with admittedly worse graphics and processors?
To play exclusives. At least I have bought all my systems so far to play games I want to play and unfortunately sometimes owning just one brand isn't enough. Good example, I still haven't get Wii, which is weird considering that I own every other nintendo console so why haven't I bought it yet? No games that arouse my interest so far but I'm sure after day or two when they release new Metroid game I'll have also Wii plugged to my TV
But to propose that Super Smash Brothers is among the top 20 game series ever made is preposterous.
I think GoG was onto something... 
Super Mario Kart [SNES] Average Press Score: 8.9 (based on 9 reviews)
Mario Kart 64 [N64] Average Press Score: 8.5 (based on 6 reviews)
Mario Kart Super Circuit [GBA] Average Press Score: 9.0 (based on 10 reviews)
Mario Kart: Double Dash!! [GC] Average Press Score: 9.0 (based on 44 reviews)
Mario Kart DS [DS] Average Press Score: 9.2 (based on 54 reviews)
Mario Kart Wii [Wii] Average Press Score: 8.4 (based on 58 reviews)
Super Smash Bros. [N64] Average Press Score: 8.3 (based on 10 reviews)
Super Smash Bros. Melee [GC] Average Press Score: 9.1 (based on 26 reviews)
Super Smash Bros. Brawl (Wii) Average Press Score: 9.4 (based on 26 reviews)
True if you like to check press scores but these are just plain fun and people of all age groups can enjoy them, no real thought required so claim that these two would be best game series ever made is absurd.