Sorry that I haven't had time to reply to this earlier in the week. Here are my thoughts. I haven't read through most of the comments yet, so I reserve the right to change my mind after I go through them. 😉

Is Burnsteem25 a good thing?

At the blockchain level

I think it's probably a good thing. Basically, I'd guess that it has reduced the Steem inflation rate by 0.2 to 0.5 percent throughout the entire course of the program. Not a huge change, but it has an impact, and it compounds over time since the new token production is a a percentage of a smaller total supply.

At the social media layer

This is what I think is more important. Participating in #burnsteem25 gives authors a way to increase their visibility and to build their audience. This is why I created the Steem Curation Extension browser extension. It provides a way for curators to highlight the authors who are participating in #burnsteem25 without actually visiting the tag. i.e. This is my feed, and I can tell at a glance who's participating.

As a curator, I definitely visit those highlighted posts first, and I don't have to spend any effort to find them. @the-gorilla did something similar in his Steemit reskin.

The key point to me (as with the previous post on club participation) is that it's not about increasing the post's value, but rather it's an audience-building tool.

Should it be kept in its current form?

IMO, the current form should be viewed as a proof of concept or a minimum viable product. It should be improved.

Should it be modified?

Yes. The tag usage should be replaced with visual indicators in the web site or browser extensions, and authors should be free to burn more or less than 25%, with viewers and curators deciding which posts they'll visit. We only have 5 tags for visibility, and if you burn one for the community, one for steemexclusive, and one for burnsteem25, you don't have much room to actually differentiate your post.

Or should it be dropped?

As long as people are participating, I don't think it should be dropped.

If #burnsteem25 went should there be some other way to burn STEEM?

Of course there is "post promotion", which I described here and @steemitblog described here.

Also, communities could require burning of STEEM/SBD as a monthly membership/subscription requirement (while muting posts from non-members).

However, I think that post promotion will only ever take off if the promotion activity is visible in regular feeds. We have seen over the years that curators don't reliably visit the /promoted page, which means that authors have little incentive to use it. The blue highlighting here shows how I handled that in the Steem Curation Extension.

What are your ideas?

It's all about visibility and usage. @null beneficiary settings and post promotion both give people a way to gain visibility, but post promotion could also give a purpose to SBDs.

After 2+ years, it's clear that we're not going to send the price of STEEM to the moon with #burnsteem25, so our focus should be on using token burning to improve things at the social media layer, not at the cryptocurrency layer. If we get the social media layer right, it might even cause growth, which could have a follow-on effect at the blockchain layer.

Lastly, here are some updated graphs at the following time frames: 1 week, 1 month, entire burnsteem25 era, and all time (left to right, top to bottom).

.	.