Sweden is 528 000 km² and there is part a geographical spread even into sea which use to have weather patterns not following those at land, part complemented heavily by hydro, and part large battery parks already in use to complement wind.
What kind of issues still remain after all these countermeasures? Still requiring countermeasures on the extremely costly scale of a massive nuclear expansion?
As other comments are on to, you can't rely on wind for base energy due to the extreme fluctuations in output. It isn't uncommon with a few days of basically no wind at all in the whole country, typically when it is at its coldest, with temperatures sometimes around -30 - -40 C in the north, and perhaps -10 - -20 C in the south. Then you gotta have stable energy, or people's lives might be at risk.
Renewables, without massive grid storage to dampen their unreliability can not be the base load upon which your grid depends.
This storage could exist, but we haven’t built it and it isn’t proven.
https://group.vattenfall.com/what-we-do/roadmap-to-fossil-fr...