Of course it's a Smash Bros rip-off. How can you even argue with that? A single look at the game already makes it obvious that they used SSB as the main source of inspiration.
Whether or not it's a bad thing can't be answered generally. However, I can understand why a developer looks down on those kind of games that make use of other people's creativity.
The most annoying part is actually that news-sites are bound to pick up the story even though Kamiya stated again and again that his Tweets aren't news sources.