You really don't want symbol interdiction. You don't use it most of the time, and the rest of the time, you're just changing a call that looks like:
foo(1, 2);
(*g_foo)(1, 2);
I wouldn't recommend -Bsymbolic by default unless you know it's safe for your environment, though. There is software that uses symbol interposition to 'productive' ends in production (not much of it, thank heavens). Mobile platforms are something of a special case.
As for myself: I've only ever used symbol interposition for debugging, instrumentation, etc . . . for which it was quite useful (as I've said). I pay attention to what my libraries export, so accidental interposition has never been a problem for me. (Making that easier by default is something that I would support.) I'll happily discuss the matter further, but I'm not interested in arguing it.
"back in the day, the startup delay for programs using
large shared libraries could be quite noticeable.
Or maybe I dreamt all of this, because I couldn't find the original article where I read it.
ELF does support load-time relocation, as appears to be done under Windows if two base addresses conflict. That just isn't the standard way of doing things, for several reasons.
First, load-time relocation imposes a cost at startup (whereas PIC imposes a smaller cost throughout the lifetime of the process). I'm given to understand that, back in the day, the startup delay for programs using large shared libraries could be quite noticeable.
Second, load-time relocation reduces in-memory text section sharing in the case where relocation is performed. If your goal in using shared libraries is saving RAM, this is a problem.
Third, it's a matter of inertia. Originally, UNIX shared libraries (a.out format) were built with a static, non-relocatable base address. Library authors had to coordinate via a central authority to ensure compatibility. PIC seemed like a good way to get as far away from that problem as possible - or so I understand.
Indirection through the GOT/PLT also serves another purpose, even in load-time relocation code - it enables replacing a symbol in one shared library with a symbol from another (eg via LD_PRELOAD). Though that's more of a side benefit than a justification.