* Churn is high, optimising user flow is mediocre at best, and iteration speed is slow, on mobile.
and
* Free is bad because of privacy blah blah blah.
I personally view the first issue as kind of un-solveable. Life is hard, etc. What are you going to do, make a HTML5 mobile application? good one.
The second, ehhhhh. Users don't give a shit about privacy. Really. Really. Like, really. Hell: I'd rather use Facebook for free and let them "sell my data" versus pay $50 a year.
Anyway, I'll reiterate my #1 learning of how startups grow into businesses. There are two ways to build a $100M company:
#1 Your users have a high LTV (=$5k+) and you can afford to spend significant (=$100+) capital on acquiring the user.
#2 Your business is massively (=10) viral, allowing you to acquire users insanely cheaply.
The reason why it is – always – very questionable to charge for a B2C user is that it's generally rather difficult to have a story that makes individual people = high LTV, ironically, without having millions of them.
You need to wrap your legs around one of these two approaches and never ever stray from it.