Agree entirely.
I think the rune page fixes were exactly the way to go.
It means new players can try out various strategies and find something they like for basically less than 1% of the cost of tier 3 runes while still getting about 2/3 of the stats (then 2/3 again because they have less slots). They used to be a noob trap but now their a cheap aid to help newer players experience different aspects of the game.
With respect to masteries, I think the reason is that it would be overwhelming to learn all at once. When I first started (April 2014) I got level 2 then saw that I had an extra rune and mastery slot. I went to my profile and looked at these then went and bought a mark and a seal for my two slots and looked at all of the available masteries and put 2 points in to attack speed (I played ADCs). When I hit level 10 I got confused about runes because I thought the Quint slots were only decoration and not an open slot so I tried to look up why I didn't get to buy a new rune at level 10 which is when I got all the rune information about it being a noob trap and stopped buying runes until level 20 (at which point I got 2/3 of a page of tier 3 runes for AD and AP pages, then filled them out with each level).
Back to masteries, it was pretty easy to see out of like 12 options at level 2 which one I wanted the most. Then each level sort of building on what I had. At level 5 it wasn't a matter of looking through all of the tier 2 masteries and seeing if I should switch trees, I just stayed in the same tree. I think the learning curve would have been immense if I had 30 points available immediately and needed to look through all 3 trees and try to figure out where to put the points. I think a lot of players would quit and just say the game is way too complicated.
I mean, you're level 30 right? How often do you write a new mastery page before a game from scratch based on who you're playing and what the enemy team comp is? I literally did that last night, but in general I don't. I have premade mastery pages that I created to go with certain champions and just select from those. Which is probably a lot better than most players - I would imagine the norm is to just look up who they're playing and copy the suggested mastery page for them without thinking. So they take the 3 defence points in armor on their top laner even though they're going against an AP top and should be taking the points in MR. Stuff like that. If people can't get it right on their own at level 30 and with years of experience and still refer to guides for it, then you can't expect new players to do it from scratch when they have no idea such guides even exist.