WireOver was born out of sheer annoyance, because it's ridiculous that sending files over WANs and LANs is still such a pain.
Our guiding principle: BE NOT ANNOYING.
Ads would be annoying, so they're out. File size limits are annoying. Failed transfers are annoying, slow transfers are annoying, cluttered UIs are annoying, not sleeping well at night because you're worried about security is annoying.
Transfers should find the fastest route automatically - over internet or LAN - and they should go seamlessly between Mac, Windows, and Linux. That's what we want ourselves as users. We'd be pleased as punch to lower the annoyance level for others too.