We've never held back anything from Ansible, really. Rather, Tower is more of a product on top that provides some extra enterprise features that most of our user bases don't need (but they should try it, because they might!).
I think if you see things like Windows being part of Ansible proper, it's clear we're not holding that back. But there are also tools the OSS community can't build easily, things that involve coordination around database schemas and (ick!) status meetings and UX mockups.
Yes, communities can build them, but occasionally, just occasionally, companies can build them better. And this is one of those cases. Our business model basically funds Ansible and also makes Tower significantly more capable that way, and it only becomes something you need when you can afford it. And it's not so much because we're a company, because I've got tons of awesome folks working in 100% full time, and that's a lot of power to build good stuff. Most likely your company employs a few folks as well :)
So on the "open core" comment, Ansible won't, for instance, ever have proprietary modules. That's something we said we don't do. Ever.
As for Tower, the small guy isn't going to need it yet. He's probably ok with pure Jenkins fronting the show. The big guy probably needs it and a super-well-tested environment and a guy to call when it has issues.
I don't know anything about other communities you've been a part of, but I think our track record shows what goes where
and people are comfortable with it. Ansible isn't open core. It's the real deal. We take that seriously.
Yet, I think the general assumption that all software has to be purely 100% open is flawed, but that in general, open source communities can build some things in GREAT fantastic ways, and certain layers do benefit from being free software. But companies need to exist. Including yours! (Though I do love me some Uber).
Anyway, ansible-pull is indeed an option if you wanted to go that wrote, or even doing image builds with Packer. Both popular options for immutable systems and/or autoscaling, sans commercial bits.
But is commercial software dirty? Heck no. Ask any SaaS company :)