Strongly influenced by the philosophy of not leaving any tracks when moving in nature, American climbers create the idea of “clean climbing”.Of course they were influenced by good old Europe, specially the idea of using nuts or knot-slings was imported by some immigrated European climbers! Using nuts and later cams to protect their climbs, it was common to remove all gear after the climb – even the few pegs, used sometimes. Granite cracks were perfect rock for that style of climbing. (Same to sandstone-cracks and basalt rock) With this special formations of rock (e.g. Yosemite) the difficulties increase permanently.
Placing trad gear requires a high routine and good climbing skills to place this gear while climbing. In perfect cracks its up to the climber to create the best distance – feeling safe and strong the nuts were in a bigger distance, than if there were hard moves with potential falls – it is always the choice of the climber, to climb with more or less gear in a line. The harder the climb, the more challenging the placement of gear – and therefore the mental strength is very important to succeed, as falls can be painful or even fatal. Trad. climbing keeps the pure style and the adventure rather high, even on small cliffs.
As not all typs of rock are easy to protect – specially if you want to enjoy slabs and pillars beside rare cracks, the placement of trad gear starts to be a real complicated deal, which sometimes destroys the pure fun of climbing – it gets more and more a game for only few, specially when climbing on limestone.
So bolting was an option to create safe and enjoyable climbs. The appearance of the bolt map a lot of new demanding lines with no limit for hard and safe moves. The protection is permanent and it is the way the bolts are placed what keeps a climb still challenging. If there are hard moves between the bolts or long falls potential.
Normatives like in indoor-climbing-walls are not the right thing. There should not be the danger of ground-falls with serious injuries, but it should be climbing not just clipping. There should be never the question of the good or bad placement/distance of a bolt, but if you are able to climb the route the way it is bolted. A bolt should never influence the grading of the climb.
Of course the bolts should be placed correctly according to all technical advises – this and a responsible distance is the responsibility of the guy bolting the line. With trad gear it is always a very personal thing of the climber to place and trust his gear – you might be happy with 3 or more in a route... the knowledge of your own climbing – ability is always the key to enjoy – in trad and bolted routes!
Finally it is the question, what kind of routes will be repeated. – Trad lines need a special community ready to play with that style. Bolted lines might be easy to repeat, specially when doing the first steps from indoor to outdoor-climbing.
There is place for both options – so respect existing trad. lines, so they are still there, when you are ready to try them – in Rum you will need that experience.
And why not play with nuts and cams in bolted lines – to get used to it and minimize the risk
https://www.mtntools.com/NutsMuseum/01.html
https://www.climbing.com/news/the-uiaa-mountain-code