I was forgetting some OpenAcs features like background delivery leverage xotcl, so I didn't think xotcl-core was a requirement for the minimal OpenACS installation, but just commonly present. This was one of the concerns.
I fully trust xotcl api, and think it gives advantages to developers, mainly related to flexibility and code reuse, but is also a different paradigm, requiring quite some cognitive load to people used to current codebase (here in Italy, most of the programming I've seen was procedural). Of course, this is not a big problem if changes happen "under the hood" in the api.
This said, it is right to move on when this gives improvement for performances and capabilities. xotcl-core is out there since a while now, so eventually a wider adoption into core codebase needs to be considered.
