Been there done that, it's demonstrably less sensitive than my Nexus 7 or S4, and even an early motoG.
2ghz is worse than 5, or harder to tell the diff at least. I sent a bunch of info to moto support awhile back,
they didn't suggest an answer but confirmed my findings. Hopefully something will happen with L.
If I'd got this phone out of the blue and not had anything to compare it to, or if I was never in finge wifi areas
that I was used to getting reception in previously, I might not have noticed. It's not crazy bad, but it's there on
more than a few examples. I have a number of side by side photos and videos showing signal strength
via wifi analyzer app and have cross checked results with netgears apps. I replaced my pretty good Asus
router with a very good Netgear, factory reset, channels are ideal and not very congested here, etc, etc, etc.
It's the phone. I'm prepared to believe at this point it is not all, or even a majority of them, but it's by far not just one here or there.
I see someone online almost weekly coming across the same problem.
All that said, I'd exchange it if I were you, and try to document if the 2nd one has the same issues via controlled situation dba readings.