Value is falling because:
1 ETH is pretty much considered an alt by most people and is thus pegged against BTC. When BTC goes up, ETH price goes down.
2 Devs with ~11 Million ETH have been selling continuously to survive.
3 Miners have likely been selling to pay bills for new purchased rigs
4 Whale investors may have been selling partially to cover initial investment risk (in fact price has gone up ~300% depending on when one invested in presale).
5 Multi-facet risks, will keep ETH price at bay:
6 Rootstock.io announcement puts ETH at some significant risk from a anybody holding BTC considering to buy ETH. If you can eventually do anything in BTC that you can with ETH, then that's a blow. Yes you can argue all kinds of ways how rootstock or BTC varients will never achieve what ETH can, but from a speculative/investment perspective it is too early to be that confident.
7 Ethereum Foundation running out of money much earlier (50% of time) than anticipated, I feel is a significant blow to ETH's price for now, as despite Vitalik's blog post on cutting costs, focusing on core and natural tendendcy for devs to start business'; let's face it, if any startup had 50% of its funding taken away, it's likelihood of ultimate success could be seriously hindered.
8 Too young - ETH is still too young and not well proven. At any time, some unforseen security risk could seriously impact it. You can't really say that re: BTC, it's been around for 5+ years, ETH ~5 months. There's no comparison. Perhaps after ~2+ years post go-live, if ETH is still around this risk should be considered lower, but look at any other turing complete system, like oh I don't know ... windows... major bugs galore even 20 years after the fact.
9 PoS uncertainty - The dev team has done an excellent job of coming up with a PoW that can't easily be ASIC'ed, although it's arguably still to early to celebrate that. The challenge with the PoW is that after 2-3 years, it's likely GPUs may not be able to properly mine it (fast block chains + too large a block chain = insufficient cycles to mine block) and PoS or worst case some other PoW is inevitable. PoS in general, for reasons above my current understanding, is not generally accepted as a long-term viable solution, thus Ethereum team has some real scientific challenges to overcome and prove, and limited time to do so. Uncertainty around this issue alone could keep ETH price relatively low.
Biggest factors that will trigger a rise:
1 CHINA - if ETH ever gets added to a Chinese exchange like OKCoin, Huobi or BTCChina, the value will skyrocket 5x to 10x in a very short time
2 Non-China Tier1 exchanges: ETH is still only tradeable on second rate exchanges with Poloniex being the biggest one. Poloniex doesn't even accept USD deposits to purchase crypto, so this keeps ETH tied to BTC price. If ETH ever gets added to Tier 1 non-China Exchange like: Bitstamp, Bitfinex, BTC-E etc, the value should start rising fairly quickly, but still nothing compared to a Chinese exchange.
3 Overall userbase - Let's face it, there are 6,700 readers in /r/Ethereum and some 180,000 in /r/bitcoin. That right there gives you a 28:1 ratio of BTC to ETH userbase. So at $412 BTC, that should put ETH at ~$14.7 right? Yes, but that doesn't include BTC china users whom probably 98% don't even read r/bitcoin.
4 Time factor - What was Bitcoin worth 4-6 months after its 2009 launch by comparison... 5-10 cents? Even if we say ETH should benefit from acceleration curve and is growing at 5x BTC rate, that still only puts the rough value at 50 cents... but 1 year from now, it could be 10x that at that acceleration rate.
5 Utility - ETH needs a killer app as somebody already mentioned. Slock.it is cool, but 24 hours after you stop drooling, you may realize that in the real world, it may not be that practical yet and even such systems that slock.it can target could easily take 1-2 years to start getting noticed by any significant audience.
6 Industry adoption - This is kind of a derivative of userbase and utility, but for example, if FinTech/R3 decides to go with Ethereum for even a private #blockchain, that ultimately also translates to Ethereum being good enough for other major players, which means its good enough for many other things. So ultimately confidence sign-off by any major industry would make a huge difference. Another is IoT itself, like the recent Slock.it example, but more specifically if Samsung/IBM or some other IETF equivalent group adopts it.
7 User Friendly soft & hard wallets - Let's face it, if you want non-geek audience to adopt ETH, well then you can't just have linux CLI wallets. Basic functions need to mature to be more easily used by wider audience.
8 Deliver on Promises - Vitalik/Gavin had some very ambitious plans, for the most part their targets are being realized but at a much slower pace than initially anticipated. Continuous delivery on original promises should help price rise, but time to deliver is also a factor. This is in fact a significant issue.
9 Speed of innovation - This is critical. Crypto competition is fierce. If BTC = Gopher, is ETH Altavista or Google? If Ethereum's claim that it can do anything any other alt-coin can do because of turing completeness that's great, but who knows what Crypto 3.0 will look like. At some point we'll go from 2.0 to 3.0 - whatever that may mean, but it's entirely likely Ethereum will one day be considered an older generation crypto.