Nintendo really do like milking their franchises dry don't they?, Mario, Zelda, etc.
Be interested to hear your justification for the phrase 'milking their franchises dry'. This year has seen Nintendo release three critically and publicly acclaimed games featuring Zelda and Mario (ignoring the characters in MK8:DE).
There has been a total of 27 Zelda games released across all formats - less than 1 per year since 1986, so it's hardly wringing out the cloth in that respect. It's a bit harder to calculate Mario games as he's a sub character in a lot of Nintendo IPs - but he is the figurehead of the company and the character on which the real success of Nintendo was forged - like the Colonel for KFC or Ronald McDonald for MD's or Sonic for SEGA.
Given the success and generally favourable global opinion of the character, why wouldn't a company capitalise on that success? It would be totally remiss of them as a business to not do so.
If Nintendo started churning out shite games every few months that sucked people's wallets dry, then that positive view amongst the public would, I'm sure, rapidly deteriorate. Instead though, Nintendo treats gamers with respect and - certainly with the main canon of Mario games - gives them memorable experiences from their time spent in Mario (and Zelda's world).
It's nowhere near as exploitative or guilty of sharp practice as those games houses which release piss poor remakes, uninspired sequels or vomit crappy DLC over and over again.