My routine is typically;
1. Shutdown any idle desktop computers in the house before going to bed.
2. Switch their power off at the wall.
3. Throw dust covers over the displays and towers.
4. Shut down any laptops which aren’t needing to be in use - as in no unsaved work or not in the middle of a project.
5. Put my few “active” laptops to sleep with the intention to use them over the next day or so.
6. Roll up any laptop power supplies and store them away together in a drawer / out of sight.
7. Slip The “active” laptops into their protective sleeves and stack them on top of my desk.
8. For my non-active laptops, I’ll remove the batteries where possible and store the batteries in sealed tubs - I tend to try to rotate usage and attempt to keep some charge in many of them.
9. The non-active laptops are then stored in protective sleeves without batteries on a rack which houses many (100+) PowerPC and early Intel portable Macs.
10. If we aren’t downloading anything, I’ll typically switch off the modem / Wifi router and wireless broadband receiver as well as put the phones onto Airplane mode while we sleep.
Although this is my personal routine, the short answer to the poll is “No, it’s fine.” - I’ve never had a problem with running my PowerPC (and Intel) Macs all night long for prolonged periods in the past, nor have I had any issues leaving things plugged into power.
I just choose to respect my belongings by showing appreciation, packing things away when not in use and covering things up - I do the same for my music equipment, books, CDs, tools, cars, motorcycle, trailer, caravan, garden equipment and so on. It’s not just the electronics that get special treatment.
It sometimes drives my wife nuts, but she can do what she wants with her stuff, and I’m sure deep down she admires my patient approach