I fully agree. It's not underrated at all, but it deserves much higher sales imo. Fantastic series. 

Yes! Metroid deserves waaaay more attention.

Sadly, Iwata is in charge of Nintendo and he doesn't care for Metroid. Since he came in power, we only got Metroid: Other M ... He off sourced it A poor 3rd party company instead of making it in house. He used those in house resources to make Wii fit, wii party, wii sports, Wii Music.

We won't get another Metroid until he has been overthrown. RISE FOR METROID, EXPOSE THE CASUAL MOBILE LOVIN' IWATA.

I don't think so because I've never played it yet I've heard it mentioned a million times. The game definitely gets its just praise

Iwata has been president since 2002.

Yes he has been president since 2002, but started making his presence felt mid/late 2006. See the connection? Me too.

I'm  not even sure I know what that means, and it is entirely subjective anyway. The fact is there were 3 Metroid games, in total, prior to his arrival at Nintendo and there have been 9 since the year he became President. That makes you initial assertion,"Since he came in power, we only got Metroid: Other M", completely invalid.

It deserves to sell more, but it is one of the best franchises. So. It is and isn't under rated depending on what context you put it in.

Well, the 2002 releases would already have been greenlit and in development prior to him becoming president.

Also 2009, Metroid Prime: Trilogy??? Doesn't really count as a new entry in the franchise.

Finally, we're now in 2015 and your chart stops at 2010... That means that barring the little flurry of Metroid loving between 2004 and 2006, it's actually been as barren under Iwata as it was previously.

extremely underrated. Probably in my top 3 franchises. I will say it suffers from lack of consistent direction. I think the reason it was at it's peak (attention wise) during the prime trilogy is because it was a trilogy all sharing gameplay styles. No one knows what the next one will be like and i think that's part of the problem. Personally i hope all 2d ones stay on handheld (or cheap eshop titles) and 3d ones stay on console. I'm more of a 3rd person player so i real enjoyed the style and gameplay of otherM (except for the really awkward 1st person moments), but i would obviously have no problem with a new prime.

While I think Nintendo should show Metroid far more love, there have been some misses in the series...
Metroid 2 wasn't particularly well received...
Metroid Prime Hunters is either hated, ignored, or completely repressed from everyone's memory...
And then there's Other M...
As iconic as Metroid is (or perhaps should be), the risks they've taken with the series have not always paid off...
And if anyone wants to know, Super Metroid, Prime, and Prime 2 are among my favorite games ever...