"What is the problem we're trying to fix"
I was on G-reg for just 3 years but I can think of a few myself which would be worth fixing.
EASA has made possible the installation of any mod previously approved elsewhere in the EU. This is a massive advance in the crappy "system" for approving modifications which plays into the hands of "design authority" sharks charging 4 digits for paperwork.
What EASA could have done is brought in a streamlined system for handling mods, particularly small mods, FAA-style, but they haven't done that. However the reality of the 'universe' (most things are made in the USA) is that despite all the hardball they are likely to eventually accept FAA STCs (like the UK CAA used to do under the now dead FAA-CAA mutual STC treaty) and that would be a massive step forward towards reality. Australia already has a blanket acceptance of FAA certification if it has an STC or has been processed by an FAA DER.
The old CAA system was pretty arbitrary. Many many mods were done under the table, with no logbook entries, because few people understood the system.
When it comes to straight maintenance, much of the industry is in such a state that you can take the plane in for an Annual and all they do is spray WD40 on the joints. Some of the worst practices are done by EASA 145 companies - the bigger the better (worse I mean). I don't think the surrounding paperwork will change this.
Will the stupid and pointless 150hr check survive under EASA? This drives owners into stupid stunts like stopping flying at 150hrs till the Annual or doing the Annual at the 150hr mark.