Each climber has an internal set of beliefs and preferences: what they like, what works for them, what drives them want to climb. Below are a few of mine.
My passion is ground up, clean traditional climbing. I don't toprope projects to suss out the moves or the gear. I use this practice when I am either attempting to repeat established lines or when I am putting up a new climb.
Why? This is more rewarding for me. It is more exciting and fun to struggle with a climb, go for it when uncertain, arrange gear under fire, depend on the quality of my gear, fall, and rise to the challenge. Of course, for those hard climbs more time is required to get a project redpointed. It also results in more falls, more sweat, more blood, and more fear. Consequently, the feeling of accomplishment is greater when the effort is done.
When establishing new routes I use bolts quite sparingly and only when they are necessary to prevent long or dangerous falls. If I can figure out a way to protect a line with clean gear it is a much better experience than simply placing a bolt and moving on.
One of the most controversial topics in climbing is the legitimacy of "agressive" cleaning, chiseling, and gluing. All of these actions can be done on some sort of continuum; generally more radical measures are used on poor rock. I do not feel any of these practices are acceptable. Steve Grossman once said "climb what is there" and I think that is a good, simple way to put it.
Keep in mind that glue use and outright chiseling is illegal on Federal land. This news is from the National Policy Director of the Access Fund.
Climbing on public property is a priviledge. We do not own the rock or have any more right to it than others. These resources are shared and limited. Because of this, each of us needs to practice responsible use of our resources. This includes:
1) Limiting our impact. Leave No Trace is an excellent resource for those who enjoy outdoor recreation. Climbers can begin limiting their impact by utilizing their suggestions.
2) For those developing routes, utilizing clean protection whereever possible and avoiding over-development.