I would argue the difference between modern bikes and old bikes for short to medium commutes (<1 hr) is immaterial. I have commuted on a carbon racing bike, an aluminum gravel bike (~£500) and a ~40 year old steel road bike I got for £20. Of course the carbon bike is very light and fast, but it has a massively greater ecological and financial cost. The aluminium gravel bike is pretty nice to ride, but not significantly different to the steel bike, which I actually find more comfortable on the road. The rotors on the gravel bike will soon need to be replaced, and that will probably be £100. I would agree with you that some modern components are better, notably corrosion resistant chains and puncture-resistant tyres. I would disagree on repair costs, in my experience, a repair at a shop in my city will cost at least £30 for something very simple like a new chain (which I can fit myself for less), and a while ago I had to pay £60 to replace a Di2 cable that got severed. (It went through the BB and I don’t have the tools to take out and refit a BB).