I love how anytime Marvel does something old time comic fans aren't comfortable with they claim it's pandering when the reverse would in fact be true. Marvel is a business and does what it thinks will be the best business decision. Fans demanded Captain America join the Avengers so Stan Lee pandered to them. Blaxploitation and Kung Fu mania were rampant in the 70s so Marvel pandered to those markets and created Luke Cage and Danny Rand. Everything Marvel does is pandering to someone, because giving the market what it wants is called capitalism. What people who don't like it are really saying is "Why isn't Marvel pandering to me? I need pandering too." Which is true. But if this change is deemed to not have as strong of a long term effect on Marvel's bottom dollar as big having it would, they will neglect you for the time being. Everything Marvel does is a gamble. Sometimes those gambles pay off (e.g. New Avengers) sometimes they don't (e.g. Avengers Assrmble).
As for creating new characters, it's been proven time and time again that this simply doesn't work (e.g. Gravity) while putting a new character into a pre-existing role has proven to work (e.g. She-Thor which outsold every Thor Odinson book since JMS). So expect Marvel to keep doing it. So if you can't handle that without chucking a hissy fit every time it happens you might as well take your buying dollar elsewhere. Because Marvel won't stop doing it until it's no longer profitable.
Whatever you do stop with the coded phrases like "pandering", "gimmick" or my favourite "it just feels wrong" while admitting a white sidekick felt right. We get it. You want to be catered to. Unfortunately it has been demonstrated that blindly catering to you means lost profits.