I agree. Or put something else in orbit that's even better.
Launch is risky, getting the observatory into proper orbit is risky, sometimes equipment doesn't work as expected, etc, etc, etc. I have high hopes for Webb, but think Hubble deserves to be saved too. Hubble is after all in orbit and doing great science, also almost to the man, the astronuat core has volunteered to do a manned mission to Hubble. I say go for it, unless a robot mission can in fact service Hubble and install the new designed for Hubble. Highly unlikely but maybe.