I largely agree - except for one thing - there is no fair use clause for patents. So when something is under patent - you can't make it even for yourself - even to experiment on...It gets really stupid when you change jobs - having signed all your IP to the first company in exchange for your salary - you can not continue to work on a project at the second without a license agreement in place if it has been patented - even if it was 100% your idea (and in the case of some contracts even if you came up with the idea at home). Clearly the rules were not written with today's technology in mind. Luckily, the letter of the law is largely ignored and hopefully it will be changed to be more maker friendly soon.
On your last point - I think you are on to something. I have never seen more hostility towards a point during one of my students' thesis defenses when he pointed out that non-engineers could design products -- the anger came from a professional engineer and I think we have only seen the tip of the iceberg. Software tools still need to be developed to guarantee safety of product components or at the very least DIY tests for the prosumers....but there is a lot of products that are not critical only beginning to be checked off.