Magenb has nailed it once again
My experience with Windriders is pretty much the same.
IF, after all the nerfs and cost increase, GW at least has left them as Troops - there would've been a reason to field them to fill up Troops slots in the Batallion. But as Fast Attack, there's simply no reason to have them in your army. They are still relatively fast, that's true, but they don't have numbers to be effective objective grabbers, and they are too expensive to act as sacrificial units (which they have to be if they're sent to grab a marker from under the enemy's nose). In addition to that, their damage output for points is poor and so is their durability for points.
With their current rules and stats, they would've been still good at their old 7th edition point cost. At their current cost, they could've been still good if they retained their 3+ save OR at least if they were Troops. They way they are, they're kind of dead in the water.
They still do what they did before. Tons of S6 shots for very little points.
Yeah, but having tons of S6 shots is not even half as good as it was before.
I've had pretty good success with them thinning out infantry and plinking wounds of vehicles. I've run two three man squads, and for around 100pts each, they are still a steal.
For almost the same points, you can field 10 Guardians in a Wave Serpent with 3 shuricannons, and that unit combination will be better at almost everything