I guess nothing wrong with the minimum deposit they set. Maybe they are not targeting those lowbies and trying to deal with people who can deposit on the minimum amount they require..
Maybe they are not targeting the lower class. But there are many countries where $15 is a lot, in my country $15=BDT 1850+. So according to my country it would be nice to reduce it a bit, there are many gamblers who gamble for fun and don't deposit many dollars. So it is better to consider all aspects.
However, this time they plan to run the signature campaign for a few months, if they get good results they may decide on a longer term.
$15 is not that high for gamblers even for lower class gamblers like me, I consider myself as low class gamblers because I do not spend much money on gambling.
Anyway I have to agree than $15 can be too high for some gamblers but I think it is a fair amount as a minimum deposit because most games available at dake.gg has minimum bet like $0.1 so it would not make senses to make a deposit like few dollars only.
If I have few dollars only, I will not force myself to gamble as I'll just keep it on my pocket because for me there is no fun to gamble with so small amount of deposit as it may lose quickly.
Of course having lower min deposit like $5-$10 will be better than $15, but the most important thing for me as small gambler is lower minimum withdrawal than lower minimum deposit.