All of those reasons, however it's not that equipment is poorly designed, it's an inevitable fact that electronic devices are easily damaged by high voltage transients.Why is "transient suppression" necessary ?
What's changed is the quantity of electronic equipment in use, from very little to almost every electrical device.
The other significant change within devices is the type of power supply used - previously 50Hz transformers and linear regulators, now virtually everything is a high frequency switching supply, with silicon devices directly on the 230V input.
Some equipment may have transient suppressors installed, but they will be Type 3 at best, which will be of little to no use unless additional Type 2 or 1 is installed for the electrical installation as a whole.