I would say that's a bit too much of a simplification. I mean it's obvious you can sell a game of a popular IP with a successful formula with game that doesn't have much synergy with it we see that often. What I'm saying is that is to truly reach critical mass it a very good way is have gameplay style that plays to unique selling point of the IP or finds a new unique selling point of the IP that you have to sell to the consumer.
I mean in regards to simply slapping on you can do that with literally any IP of similar popularity you probably won't get much difference. The reason why an IP is as big as it is in the first is that it will have a set of strengths. If your leveraging that IP it's far more easier to appeal to a consumer (even more casual and tertiary consumers) through playing to that set of strengths rather than applying it to something it may not synergies well will it. Basically taking the unique selling point and translating it in a way that makes sense in mobile rather than the opposite. The issue with this is having strong IP's and they don't exactly grow on trees.
Okay, but... what is your disagreement with Matsuda then?
Like even if we look at something like Brave Exvius, their best performing Final Fantasy title, it takes the gameplay setup of Brave Frontier, and then modifies and expands it quite a bit to fit the feeling of playing Final Fantasy. A lot of other mobile JRPGs aren't set up like that as well with exploration areas and towns and the like.
He's basically saying he wants to go more in that direction, or potentially go significantly afield of what's currently on the market to try and stand out. Their next mobile release is a mobile MOBA for example, of which there aren't a ton, and none are doing well in Japan. Mind, that's a game that was announced a long time ago.
I don't think either approach (either a new IP with notable divergent gameplay, or an existing one that notably molds a formula to fit the IP) is exactly outrageous under the context of wanting to stand out more.