I think people are not seeing another big issue with an unlocked premine of this size, and it's simple market manipulation.
Dero reached a rather sizable ATH back in January before the market took a dump. A premine of this size would allow for massive sell opportunities, only to buy in again at the bottom. The same can be said as of now, with Dero at 30% of the price it was a month or two ago.
These "untouched" premine totals can be completely fabricated, since the dev can play with this stack on the market, force a massive dump, then buy back enough dero with a 70% discount to keep the same amount of premine, except with rather substantial gains made along the way.
I do not disagree, but there is also a more subtle and insidious effect that a sizeable premine cannot help but have: it centralizes control of the network under the premine holder, for as long as it exists.
The community puts their money into a project, so what happens if/when the original developer goes off the rails? If the source is open, the community can wrest control of the network by forking. However, say that 20% of existing coins are currently held in premine; in this case, the community cannot take over without massively rewarding the very developer from whom they wish to take control, while at the same time, taking a hit (in terms of value) themselves.
As such, projects which have sizeable premines, and/or closed code, can hardly be called decentralized.