Anyway, I think the biggest problem here is that some people think that new platform =new generation.
The Sega CD, the Sega 32x, the Satellaview and the Nintendo DSi are new platforms, because they have game released exclusively on them. However, they are not new generations, as the MegaDrive, the SNES and the Nintendo DS continued to have a full-fledged support from the platfom holder and major third-parties. They co-exist with the main, more supported and more popular platform and are therefore part of the same generation.
On the other hand, the Saturn, the PS2 and the 3DS are not only "new platforms", but also "new generations", as the platform holders started developing games exclusively on them, along side major third-parties. They replace the market of their precedessor. Note that a significantly spech-bump is not necessarily. Wii was the successor to the GameCube, but it hadn't a significantly spech-bump. The PC-Engine was a 8bit system, yet was not part of the same generatione as the NES.
As some already pointed out the GBC had tons of AAA (for that era) exclusives. Oracle of Ages/Season, Metal Gear Solid, Shantae, WarLord, Resident Evil, Wario Land 3, Super Mario Bros. DX, Kirby Tilt 'n' Tumble and so on. Even small developers made their game GBC-exclusive.
This means that if you had a OG GB you couldn't experience the latest portable games. Just like if you had a PS1 you couldn't play the latest console games. Of course, OG GB was a very popular platform and they continued to support it for a bit, expecially with cross-gen titles.