Earlier quoted context omitted.
Ads on the lockscreen may be fine from a UX perspective, however, that tablet is now using data when it's a sleep which becomes a factor when someone is on a capped connection. Sure, it may only be a handful of MB/month, but to some people, every MB counts.
I believe this thing only has wifi, so that's not a relevant problem.
Its not some free magical data flying around on its own.