I totally agree. Distros are changing into two different groups these
days:
- everything tied together and intregrated nicely for a specific
kernel version, userspace tool versions, etc.
- flexible and works with multiple kernel versions, different
userspace tools, etc.
Distros in the first category are the "enterprise" releases (RHEL, SLES,
etc.), as well as some consumer oriented distros (SuSE, Ubuntu, Fedora
possibly.)
More flexible distros that handle different kernel versions are Gentoo,
Debian, and probably Fedora.
And this is a natural progression as people try to provide a more
complete "solution" for users.
When people to complain that they can't run a "kernel-of-the-day" on
their "enterprise" distro, they are not realizing that that distro was
just not developed to support that kind of thing at all.
So, in short, if you are going to do kernel development, pick a distro
that handles different kernel versions. Likewise, if you are doing
userspace development (X.org, HAL, KDE, Gnome, etc.) you pick a distro
that allows you to change that level of the stack.