Oh no! In their efforts to balance to an appropriate median for engaging gameplay, Bethesda nerfed your favourite perk? This looks like a job for needless modding!

Puts MacCready's perk bonus back to the old +2000% (instead of the proper +20%), as well as change the description to reflect it.
Under Cheats and God Items because of course it is, don't pretend this is normal. "lol if its in teh game its intended" YOU ARE THE WORST TYPE OF PERSON. But enjoy.

I've also included the 'fixed' version I used to help with testing, just in case you want to fix the problem without downloading the beta patch before its official release.

TO ADD OR REMOVE
Install by dragging the unzipped *.esp into your Fallout4/Data folder. Enable using NMM or by modifying your plugins.ini file.
Don't know why it isn't working? You might not have set up for mods yet. Follow directions on this guide.
To remove, delete or disable the *.esp. For safest file handling, revert to a save before installation.