Long story short:
1) the population has gone up a lot, so all infrastructure (traffic, electricity, water, housing, etc.) has had to increase rapidly
2) the mix 10 years ago was a lot of coal and oil, now it is much more natgas, wind, and solar. These can be reliable, but they are very different than coal and oil, and therefore a lot of new lessons have to be learned.
3) a big reason for the surge in renewables is the way the market is designed, which lets them pocket big bonuses at peak demand times. Since this _normally_ is in the summer during the day, this makes solar a lot more competitive financially. Natgas certainly failed in February, but all three of wind, solar, and natgas had big problems, it was just that the natgas and wind were unexpected while the solar was not (in the winter at night).
Thus far, the power grid is holding this summer, even though there is all-time record demand. We certainly do need to increase capacity, but that is mostly due to the surge in population, not any huge mismanagement. I'm sure it could be done better, but it's not unusual for record demand and a new mix of sources to put the system through a learning curve.