More important than Psyduck for sure. XD
Erhem... now, joking aside.
StarTropics had two games. The ONLY reason why it did NOT become popular was because it was not released in Japan. It was intended for a western audience... The japanese learned from their mistake and never again made a franchise exclusively for western audiences (until perhaps Pilot Wings).
Anyway... why's it important?
Well... Mike is a MAIN character, and not from one game... from TWO games on the NES.
Sure... they're overlooked, and not popular... but since when did popularity affect how good games are?
I'm not just randomly spitting suggestions here... It's time for this game to be represented in SSB somehow... Perhaps they didn't give Startropics a single trophy in Melee, fearing some kind of uproar, or something.. Because this game beats the 2 original Zeldas in so many ways it's not even funny...
Sidenote: Startropics was made by the same man behind Punch Out, just so you have a clue of what type of mind worked on it.

(he also made the save chip used in Zelda for the first time).