Development on these scales is somewhere between blazingly fast and fairly moderate.
It's silly to say core won't accept help, given that the code is in git. Did you submit a pull request that was rejected? No? Then what are you up about?
The "size issue" is a non-issue as long as one can easily run a fullnode. There is no time-scale on which you can reasonably project that it will be difficult to run a full-node on high-end commodity hardware. Given thin-clients, what more do you need? Thin clients are in development.
EDIT: I thought you were referring to the recurrent criticism that the blockchain is larger than bitcoin's. I suspect you were referring to transaction size. That is addressed by tacotime, below.
In short, everything you mentioned as a problem was not, in fact, a problem, with the possible exception of the fact that the website is neglected, but not much. It could use a few periodic updates, perhaps some more external links, but it covers what it really needs to cover.
I agree with Mumbles. I'm a humble troll but I speak the truth when needed. Any coin, that includes Bitcoin, Monero, Darkcoin, etc needs good marketing, not everyone is a genius crypto specialist, most people need fancy graphics and text to instill confidence. That means having a good looking website and etc.
and people here don't help the noobs such as me :\
For installing your wallet on windows, you have this monero wallet tutorial
https://monerotalk.org/t/bounty-create-a-useful-tutorial-on-how-to-setup-monero/13/8