That's a good reason. I've taken to quitting at the end of the second week for several additional reasons, which I'll list here:
First, it avoids the risk of failing to recognize "not so good numbers" as the Sensor begins to fail. (Which could occur at night, and could also happen away from home.) Second, it's unlikely that I'll have the replacement Sensor just "lying around" away from my home environment. I might not have a skin-prep pad either, and I definitely won't have a portable hairdryer keep the drying skin-prep from flowing downwards as it dries. (That leads to an inconsistent layer of skin-prep, thinner at the top of the area. The top edge is the place where Dexcom Sensor pads usually fail.) And I definitely won't have the big bottle of Povidone-Iodine which I use to disinfect.
Finally, of course, messing around with the 2-hour startup for only 2-4 days of additional readings isn't worth the hassle, and it's likely to occur at a time when you really wanted to be getting good readings.
Switching from one week to two cuts my co-pay costs in half, but switching from 14 to 17 days (typical) provides only 18% more savings-- which isn't worth the risk and hassles for me. People with worse insurance, and/or less income, might want to push their Sensors to the very end; but for me, it isn't worth it.