Why don't we learn from the past ?

Yup. Cambelts are going out of fashion - probably because some modern cars are starting to do silly mileage so the interval comes around far too soon.

Personally, I prefer the gear driven camshaft in my 2CV. Chains can snap too!

Changing a cambelt - how difficult is it to redo the timing?

I changed the cambelt on a Polo, took me just over an hour and I didn't have a handbook, most of the right tools, much enthusiasm.... With some cars you can push the belt backwards (towards the engine block) then start to put the new belt on. Then you can cut the old belt off and push the new one all the way on, no chance of the cam and crank getting mis-timed.

Don't forget to make sure the cambelt tensioner is working ok while you're in there!

The reasons for belts instead of chains are mainly cost and noise from a manufacturer's point of view. As said above, camchains can snap too!

cam belts are quieter, cheaper and lighter and as long as they are inspected and changed when they should be they should give no bother, chains last longer generally but can be seriously compromised by missed oil changes and bad maintenace, both have advantages and disadvantages but neither should be any risk if looked after properly.

My 24v has a single duplex chain which lasts for donkeys despite the fact that these engines are known to eat the chain guides and tensioners, the later BOB version went to dual chains with one chain per bank, not a great idea cos if one side snaps the engine will keep running on 3 pots while hammering the pistons into the valves on the other bank!

I like cambelts, OK youve gotta change em, but I reckon they are a better solution than a fuggin bicycle chain, lighter quieter + cheaper.

they're only really a problem when they snap and instantaneously destroy your engine causing out-and-out financial meltdown and subsequent poverty => homelessness => malaria etc.

mines given me Crabs

My Tatra had a triplex timing chain on the hemi V8, still needed replacing after a mere 300-400k miles

chains easily out last belts, much better and less bother in the long run.

Haven't recent, err, This decades Astras & Vectras got a bit of a reputation for chewing them out earlier than most.
Though workmate had his water-pump seize, striping timing belt, smashing valves. Maybe they're trying to do too much with them? Like Lancia Gammas reputation for snapping belts with the extra load of the power steering pump?