There's nothing wrong about changing block reward as long as it's a change that makes sense. Dogecoin started with a random block reward like Luckycoin, which code was used for the coin, and then changed it to 250,000 fixed and continued its reward halving schedule. Dogecoin supply was meant to be capped but they discovered a bug in the code that would make it not be capped. Then IIRC Jackson Palmer though it was a good idea to keep it uncapped and there was no problem about that. Coins can have many problems (wolong, moolah). Block reward changing is not one of them.

Edit: typo