Partly because of "sustainability" component, partly because of general considerations.

A bit offtopic on the latter: the current "green energy" movement seems to be much more political than rational, onten pushing for the so-called "eco energy sources" without any regard on how these will integrate into the overall electric consumption balance. For example, one of the crucial elements of last-year Texas energy crisis was over-reliance on the renewable energy sources (solar and wind) while decommissioning the ecology-unfriendly coal and gas plants which served as balancing reserves, so at the moment of partial power outage due to freezes the rest of electric grid couldn't refill in time, which caused a cascade effect. It wasn't the only cause (cue the state economy on expensive gas supplies and historical electric network desync on a federal scale), but it can be considered as a "last straw" in that particular event.

The problem here is not the overall power amount, but the power density. What a wind turbine produces in years, a regular steel or aluminium mill (or a production line for fiberglass which the same turbine blades are built of) consumes in days or less.

Basically, one cannot fabricate new wind turbines and even replace decommissioned ones using wind electricity only, another high-density energy sources are needed for it.

>Are wind turbines good for the environment?

Depends on what you want to compare it against.

There are quite limited ways of recycling for the decommissioned wind turbine blades, as their primary material (fiberglass) isn't naturally degradable. Main problem with mechanical recycling is that it's also power-consuming, which often makes it net negative in either financial costs or energy costs. Which in turn makes burying and landfilling more "economically reasonable".

Wind electricity production fluctuates time-wise due to windstreams being irregular over time (from daily to seasonal), which requires accumulator/battery buffering systems to smooth discrepancies between production and consumption spikes ^({or just a coal power plant nearby}). Most effective types of batteries are based on lithium chemistry, and lithium mining and production is very environmental-unfriendly. There are specific buffering technologies based on salt melting or natural gas liquefying, but they are not cheap enough and low-efficient in general ^({however, with current liquefied gas prices in the world it still can be at least profitable}).

Also, wind generators have quite low electric power output. It is fine for feeding general population needs, but almost inapplicable for power-hungry production industry. That limits application of wind energy severely.

Therefore, if one takes into account the overall fabrication and commission cycle as a whole (not just "pure electricity production" part), it turns out that wind turbines are worse for environment then e.g. natural gas turbines or nuclear plants. Still better than coal plants though.

^({On the sake of somehow-invisible comments: I speak about "environmental damage" in general (including all ways of ecosystem harm combined, not just greenhouse emissions. On the latter, things that burn are obviously more influential than things that don't.})