I just happend to stumple over the interest precentage of other major coins and ethereum is eye catching.
With a bit more than 7% (was even a lot more in the last months) and DASH with 6% I understand that a flow to ethereum might have happened and played a role in the devalue of DASH.
Now with the masternode reward increaseing and the ethereum interest decreaseing (Only 11% ethereum are stacking and with more it becomes less interest) DASH might get back into a more interesting region for a coin investor with a height interest in mind.
It's not as simple as just comparing percentage staking rewards between coins because:
1. ROI isn't calculated that way, it's calculated on the dollar value percentage gain, not the staking reward ratio
2. It includes the capital gain or loss on the collateral which your comparison doesn't account for
3. Point 2 is dependent on the speculative confidence in growth of the marketcap of the chain
With regard to point 3, Ethereum's monetary value basis is to a large extent the absorption of new supply by on-chain services and applications (we saw that with, for example, the insane valuations it reached during the CryptoKitties craze). With Dash it's scarcity value which is supported by mining, same as bitcoin, litecoin XMR, Dogue et al. Consequently with Ethereum, its value basis is growing (due to growth in on-chain apps), with Dash it's diminishing relatively (due to progressive mining deficit as a consequence of protocol changes).
So, since stakers are so exposed to capital gain/losses on their collateral, this blows away any small differences in staking reward percentages as to make them irrelevant. This is why setting the reward ratio at the right level for maximum capital gain is far more critical than setting it for maximum staking income.
P.S. I've just stumbled across the first piece of inspirational commentary I've seen from the Dash community in a long time. This here is exactly what's needed. The whole problem is that Dash is increasingly being run like a corporation - both in economic and governance terms. Economically, mining was seen as an "overhead" which it would be if we modelled Dash production like a product, but from a monetary crypto perspective is simply ludicrous. From a governance perspective it has turned the voting community into a herd mentality zone which delegates all its thinking to "the Dash government" instead of issuing them instructions. I could go on but the jist of this post is why we're being trounced by the likes of LTC, XMR, BCH, ECT...they are able to attract talent on a granular basis without relying on a single contractor for everything.