Any add-on that uses absolute paths anywhere in the add-on will stop working if you rename it. For example: Say you have an add-on called "Weapon_MyGun" and it has a datablock in it that uses "Add-Ons/Weapon_MyGun/model.dts". If rename the add-on to "Weapon_Gun2", model.dts is now in a different place and the add-on will not work.
Namecheck.txt is an extra check on the name of the add-on to prevent morons like Blocki from renaming it and breaking everything.