MakerDAO is the first true stablecoin for Ethereum. Unlike Tether which has a central point of failure the Dai is truly decentralized. Dai is supposed to always be worth more than $1 and so far while it is still within 1 cent of a USD it is showing as a proof of concept that it can work. We on Steem have the Steem Dollar which has a lot of variance in price so from a point of view of being a stablecoin the Steem Dollar is not exactly stable. The Dai if it can prove to be stable can be a place to hold value.
What about the change in the law which makes crypto to crypto trades taxable? It is because of the capital gains taxes that even holding Dai might not be idea. That said there are still reasons to hold wealth in Dai on Ethereum besides unregulated decentralized exchanges. The success of Dai will improve the utility of Ethereum for the better in the long term but Ethereum still has some problems to solve.
I think it makes sense for me to hold Ethereum because I think sharding will make Ethereum scalable. Theoretically the evidence suggests that sharding can work. Proof of Stake is controversial but the hybrid approach will give the community time to find out the risks vs benefits of Proof of Stake.