I guess this is because of the amount to be broken down into smaller transactions, i.e. 123.4567 => 100 + 20 + 3 + 0.4 + 0.05 + 0.006 + 0.0007. I think this way will increase number of inputs enormously. If this is corrent, Monero need some serious improvements otherwise it will be struggle on getting more adoption, we can't tell user to send coins in even amount of something like 100 XMR instead of 100.123456789 XMR.
the problem are many small inputs (eg pool payouts)
btw bitcoin has the same problem (just better pools)
So will this problem will be less seen while XMR continue growing ?
yes obviously. It doesnt even need to grow. Pools just need to limit payouts...