My thoughts on the whole bolting ethics are to just use common sense on what it good for everyone not just yourself. Over-bolting, and over-cleaning will just lead to more damage of the rock, more negative press, etc.
I completely agree with replacing existing bolts and anchors to bring them into the 21st century. However, one should not randomly go about this. The replacement should either consist of the single bad bolt, or the full route (including both anchors as necessary). To only do half is laziness. People may complain about the cost of bolts as the reason why they only did half, but I am sure if they posted here about their project, enough people would give to the cause to make the cost not too bad.
I also think that Index should not be grid bolted. There are many faces at Index that can be bolted, many variations to be climbed and such. However, this will just lead to chaos like Exit 38. There are so many good lines at Index, that hooking them together is not necessary. If you feel that you need to climb that blank space between climbs, top rope it.