Hello, is it intended that the wood ore has such a high mining time, and if yes, can you tell me why?

It looks like the mining time is for the sake of balance. Because now you can automate wood gathering, and unlike other mods, you don't have to run a greenhouse setup and worry about by-products. I use some mods that let me use wood for other processes (like charcoal or oil), so this mod is still useful as an early game source of automation.
If you look at greenhouses in mods like Krastorio 2, really it's the same thing. You expend water and power, then wait a bit, then you get some automatic wood production.

I already have Bio Industries for automatic wood production, I just wanted an easy wood source in the early game, but I now found Robot Treefarm, which gives me an easy early source of wood and also kind of makes Greenhouses obsolete