Sure, and I've always been careful to give the Lustre folk credit for the work that they did between 2003 and 2006 extending ext3 to add support for delayed allocation (which JFS didn't have), multi-block allocation (which JFS didn't have) and extents (OK, JFS had extents).
But you can't have it both ways. If that code had been in use by paying Lustre companies, then it's hardly alpha code, wouldn't you agree?
And why did the Lustre developers at Clustrefs chose ext3? Because the engineers they hired knew ext3, since it was a community-supported distribution, whereas JFS was controlled by a core team that was all IBM'ers, and hardly anyone outside of IBM was available who knew JFS really well.
But as others have already pointed out, there was no grand conspiracy to pick ext2/3/4 over its competition. It won partially due to its installed base, and partially because of the availability of developers who understood it (and books written about it, etc., etc., etc.) The way you've been writing you seem to think there was some secret cabal (at Red Hat?) that made these decisions, and there was a "mistake" because they didn't chose your favorite file systems.
The reality is that file systems all have trade-offs, and what's good for some people are not so great for others. Take a look at some of the benchmarks at btrfs.boxacle.net; they're a bit old, but they are well done, and they show that across many different workloads at that time (2-3 years ago) there was no one single file system that was the best across all of the different workloads. So anyone who only uses a single workload, or a single hardware configuration, and tries to use that to prove that their favorite file system is the "best" is trying to sell you something, or who is a slashdot kiddie who has a fan-favorite file system. The reality is a lot more complicated than that, and it's not just about performance. (Truth be told, for many/most uses cases, the file system is not the bottleneck.) Issues like availability of engineers to support the file system in a commercial product, the maturity of the userspace support tools, ease of maintainability, etc. are at least as important if not more so.