Yes, I do. I can't necessarily rationalise it entirely and I know that different people have very different views on this.

Here goes. The obscure sites need protecting, but from irrepairable damage. Upland cairns are not damaged by people sitting on them or climbing on them, you have to make a big effort to move any stones (ask Lubin how difficult it is to restore one that's been messed about with). Similarly, most barrows in fields aren't damaged by occasional visitors walking over them. But they are damaged by constant livestock erosion and incremental ploughing. I think - to me- it comes down to what will actually cause damage. If loads of people start visiting a little barrow in the middle of nowhere, it may become at risk of damage from those visits - but most aren't in danger of that happening, so visiting, taking pictures, recording any existing damage (which might not be apparent from below, particularly where the damage is an excavation into the top) has value, which can be weighed against the possible damage (if any) caused by the act of visiting itself. But Silbury is definitely at risk, because lots of people would love to climb it if they thought they could do so legitimately - far more than climb it now clandestinely. So the risk of damage is very real and one person climbing it will be seen by others as an endorsement of a view that it's okay to do so. There are also lots of well-known sites that are finely balanced, examples being West Kennet, Wayland's Smithy, where it would be lot better if people kept off the mound as it is noticeable getting worn.

I know that really there's no difference on lots of levels with climbing another less-known barrow, but in truth the consequences are likely to be very different. Volume of visitors (and the precise behaviour of them) makes it different.

Obviously, if your objections are based on belief rather than damage, that makes for an entirely different view, i.e. you wouldn't climb on any barrow, even if you knew it would cause no damage, because you believe it is disrespectful - I don't share this view, I'll be honest. Dead is dead, as someone said. Everyone walks over multiple graves in any medieval churchyard, but I don't think it's disrespectful to do so.

That's the best I can do, this late on a schoolnight!