All features and new functionalities described in
https://en.bitcoin.it/wiki/Contracts are very fascinating. But when would these features be enabled in Bitcoin? When would these complex transactions become "standard" transactions? When would such features be included in a BIP?
They're already included since day one. Many of them have long been standard transactions, but for those who are not they don't need to be standard transactions to use them, develop tools for them, or experiment with them. Since a month ago in Master, practically any script encoded as P2SH IsStandard in any case.
Sadly there seems to be fairly little true interest in doing anything advanced or at least in building tools to make things usable to laymen.
There is no need to create a BIP for features that already part of the protocol, though if some transaction form becomes common and people might want to make interoperable implementations and at that point writing up a specification to help front end implementations interop might make sense, but it wouldn't be a bitcoin protocol thing.