So, a few things to clear up.
Our houses are insulated, BUT we have concrete slab foundations that suck the heat out during the cold. Windows are usually an issue too for a lot of people. My house is around 4 years old so I don't really have those issues aside from the cold foundation. I also paid to "upgrade" to blown in insulation. I wanted spray foam on the outside and rockwool around at least the theater, but I got blown in.
My garage is also insulated so my water heaters don't have to work all that hard. I'd say the coldest I've ever felt it in my garage was when it was 8F out a few days ago. It felt like maybe 45F. Usually it's as low as 55F and won't really go above 80F in the summer, unless you open the door.
Energy in TX can be cheap depending on where you live. When I was in the DFW area we had the
powertochoose site that lets us compare rates from tons of different companies. However, not all cities are like that. I lived in Lubbock (300k people or so) and there was ONE choice. Same with where I live now. You want power, you pay what they bill you. Solar is HUGE down here, but I won't bite until the solar roofing material Tesla makes is available here.
In the heat of the summer, ~100F or so, I try to keep it around the same temp as you and my bill is around $400. However, that is also my water bill and garbage bill, so my usage isn't that bad. That's also with multiple PCs and servers running. Not to mention garage fridge, chest freezer and all that. I'm glad I made sure to get a well insulated home. I've had the opposite and it sucks.