I see that the usual Monero supporters are flowing in and try to go off-topic, but the thread is still "What is Monero's Problem?". Please try to throw in your ideas/bulletpoints and don't come with the "Monero is pefect as is", the price action seems to indicate something else.
Good call. As a "monero supporter", but in general a cryptocurrency supporter looking for a viable solution for a trustless, decentralized value storage and transfer system, I think the problems with Monero are as follows:
1) Difficult and purposefully obfuscated inherited codebase. Because Monero was forked from bytecoin, and in an attempt to secure their code from forks and/or hide the scamminess (de-optimized miner, for example) the bytecoin developers removed all comments from the code, Monero is notoriously difficult to develop. I have witnessed numbers of developers pop into the IRC channel and have an interest in working on the code, only to be met with "Yeah, thats not documented that well and the dude that knows that section isn't here right now, but if you stick around they'll probably pop back in."
This problem is slowly getting better through the natural process of monero developers commenting code as they improve the software, and the direct funding of developers to painstakingly go through the codebase and document it. See here:
https://forum.getmonero.org/22/completed-tasks/2373/documentation-and-cleanup-of-source-code 2) "The Monero Problem" that I outlined here: https://bitcointalksearch.org/topic/m.14588629This might actually be a cool cryptography problem that is borne of the fact that for a ring signature, you need to select outputs, and the distribution of output selection might lead to information leak of some kind. I was hoping this would intrigue TPTB_need_war, but it didn't. Oh well. I think i came across a good search term "cryptography subset selection" might have led me to one article in the literature, but there wasn't much else.
The solution to this problem is being actively researched (or at least thought about) by some people.
3) Auto fee adjustmentI hold the opinion that the best cryptocurrency network is the network that does not need human intervention to adapt to existing conditions. Currently, most (all?) cryptocurrency networks use a minimum transaction fee mechanisms as a means to prevent network flooding. This minimum fee requires manual adjusting as the "fiat" price of the currency changes. How to automatically adjust this fee is a matter of ongoing research.
In my opinion, these are the 3 primary technical hurdles.
The rest of Monero's "problems" relate to the unique result of fusing free open source software directly to money.
Edited to add:
I'll add a final problem. I can't code. This tech fascinates me so much if I could turn my thoughts into bits there'd probably be another 100 commits, at least. Instead I just write bash scripts to make it easier for others to use.