If cave wants to pull in "filthy casuals" without creating shitty games that will annoy its long term fans, it should follow in ZUN's glorious strides, namely, creating a large cast of beautiful girls that people will write a lot of doujin porn about. And I don't mean shitty robo girls with such edge that you can't even shake their hand without having your hitbox grazed, I mean honest to goodness "healing-anime"-style flat-chested girls who are over 1000 years old so that it's okay to fap to them. Because, I mean seriously, think about your favorite fictional universe, think about what lead you to first really dive into it (;)

) and think about what makes you keep coming back for more. Okay so this is a bit lewd, but mastur"bait" is literally the ideal mechanism by which a series both captures fans and develops loyalty. And not like "uuu~ sayaka-chan is so moe I'm gonna DIEEEEEEE (and so is SHEEE xdDDDDD)" but I mean like thousands of gigabytes of lossily-compressed doujin arranges of the music and even culture SO DEEP that it gets studied at
Oxford (no actually wait for the banner to change a couple of times, it's a real 2hu being discussed by real academics).
I think the key is time scale. If you think about your most rapid improvement in shmups, it likely happened in an era where you practiced consistently for like 2 hours a day maybe. Not that random week over the summer where you played 20 hours a day and then burned out, not during finals week when you binged on the weekened and then stopped playing when your exams started and you had to cram, but just consistent short periods. And masturbation forces you to engage in PRECISELY this schedule. Masturbating to fan works of a series is the single most efficient way to both develop a knowledge of the universe (fictional AND real) as well as to develop technique with respect to said universe.
Just my two cents.