Yes, make us proud, by actually using the filesystem's capabilities and not further discouraging the proper use of fsync (not overuse, such as firefox is/has been prone to...) by keeping it unnecessarily slow (which alloc-on-commit will do).
The kludges for alloc-on-replace that will apparently be enabled by default should deal with the real, problematic cases of loss of pre-existing data quite nicely, and I do think having those as defaults is a good, reasonable compromise. Those who want to be extra-paranoid with either nodelalloc or alloc-on-commit, well, sure, the option is/will be there, but I don't think these might I say somewhat obsolescent modes should be the default.
'course, distros shouldn't use ext4 per default yet anyway for conservativeness sake. Maybe starting next year ;]