What do you rejoice? It is advantageous when your speed is higher than the other. And when the rate rises in all, you are in relation to other, standing pat are.
It just kills the coin.
Exactly - the only one actually making money is Claymore xD
If you check history, my miner is not x3 faster than others, I just see how fast others miners and release a bit faster version. This time I have to release faster version due to new miner. If people stop this speed racing I'll stop it too, but you know it won't work

Also do note my miner is not for NVidia, not for CPU and not for Linux, so if I release miner with x2 speed, network difficult is not going to raise x2 too.
Faster public miners don't kill coins! Private miners which could concentrate hash power in a few big farms may be nocive for the coins if they are a lot faster than public ones.
Faster public miners on the contrary, help with a more diversified distribution, lowering the impact of private miners.
The price is declining because zcash was overpriced due to the low initial mining rewards which leads to a very low initial supply.
The total emission will be 21 millions of coins like bitcoin or like monero in 2040: Expecting the price could be maintened around 1 btc is unreasonnable for short/medium term. I would expect price going in the 0.005-0.05 range.