I personally run a MITM proxy on my network which all traffic goes through. IMHO the security concerns are overblown and largely come from companies like Google trying to stop people doing things like this. They are only securing their profits, nothing more and nothing less.
These changes aim to improve the ads experience, tighten security and limit misinformation according to the company.
The truth is probably closer to "increase the number of ads you see, secure you from getting around that, and limit the proliferation of anything but their official propaganda."