That was decades ago. The quote in the OP is talking about here and now.

 Meh. Far as I can tell, they haven't changed much. 

No offense, but I'm more inclined to believe the guy who has actually just finished making a game with them.

 And I'm inclined to believe the other 95% of the third party industry that says otherwise. We can agree to disagree though lol

And where are all these sources saying Nintendo isn't open to creative new ideas?

Can you stop coming to a thread with nothing but flammatory comments? I mean I troll on this forums but this is just low.

That's definitely good, and they should continue doing more of this. They've done well to have some new ones like Splatoon and ARMS, but I think they could use a few more new ones if they're gonna break away from being 'That Mario and Zelda' company.

Well more like the 'mario and zelda and pokemon' company, which are more 5mil+ franchises than most devs out there in the first place (esp. Considering mario kart and smash also go 5 mil+) so...

I think most companies that come to them with the right idea ( i.e. not just reskinning a game they already made or planned on making using their characters differently) or tone wind out finding this, I mean Platinum with Bayonetta 1 and 2, said similar things.

The ones that usually complain about Nintendo are either those have had problems with their developer support not being on point, the hardware or those that have some sort of bias against the company due to other circumstances. When it comes to games that feature their characters, so long as they aren't widely going against the property's image (i.e. Kirby being confirmed as a genocidal tyrant or one of the human looking characters in their underwear) and the game is good Nintendo is usually cool.

Considering their beloved IPs are their lifeblood, Nintendo have been fairly liberal in letting third parties work with them, from Mario + Rabbids to Hyrule/Fire Emblem Warriors.