A good reason is that there may well be situations where spending more than a fixed percentage of the market cap per year is beneficial or even necessary.

For example, consider a situation where a major rearchitecting of the code is needed to deal with a looming scaling issue or such. Now, right now Hive is getting most of its development for free, but that could stop at any time, and it might be necessary to spend a lot in a short time. Or, more conventionally, there may be marketing opportunities that, while expensive, Hive stakeholders are convinced will dramatically increase the visibility and user uptake. It may turn out that they are wrong, but it's okay to believe in something and try it, and if something like that does work out, an increase in market cap of even 20-50% (and it could be far more) can easily far more than make up for a few percent more in inflation.

I really see your approach as paternalistic in believing that your notion of how much (or more precisely how little) should be spent at any given time is better than the collective wisdom of stakeholders voting on the DHF. I don't agree with this. I also don't think that low or fixed inflation, in and of itself, is particularly valuable for an obscure blockchain that is one of thousands. Anyone who wants to bet on hard money as a key driving value proposition can find dozens or maybe hundreds of better ways to do so.

And, to be clear, I am writing this as someone who has often voted no on expenditures, in the sense that I voted for return and didn't vote for many of the passing proposals. But when I was outvoted, I accept that stakeholders disagreed with me, and I don't really know who was right.

If we want to emerge from obscurity, we have to take big risks and that can mean spending big money, not necessarily just a small percentage of market cap per year with stakeholders obsessing over their share of a shrinking pie (or melting ice cream cone might be a more apt confectionery analogy).