Listen, if you're a gamer who is able to play Viper optimally without ever drifting your GCD or losing boss uptime while also perfectly dodging all mechanics in savage boss encounters, and you think it needs to be even MORE challenging by adding complexity to its rotation that requires pre-planning, I really am sorry that they did this to you.
But I suspect most people who are complaining about this aren't actually able to do that.
Viper is very much like Black Mage. The challenge isn't in the rotation, it's pretty easy to do on a targeting dummy. The challenge is doing the rotation with as little loss of uptime as possible, with the understanding that you don't bring anything except damage, so you have nothing to fall back on to contribute to the group if you play sub-optimally.