Not neccesarily.
There's been plenty of exploits posted for a lot of games on these forums and most were never patched.
Tends to vary by how easy the exploit is.
For example, a couple of repeatable speech checks in Fallout 3 were patched out. For good reason, you could just spam over and over for an easy 500XP at a time and level up with no effort.
On the flip side, the 'Gary Exploit' from Operation Anchorage that allowed you to bring the non-degrading versions of the weapons and armor back from the sim was never patched out, due to it's difficulty. Likewise, the 'paintbrush ladder' from Oblivion was never patched out either.