Distributing classes suit investors drawing an income and those in tax systems where a received distribution is simpler to report than a notional one. The share price drops by roughly the distribution amount on the ex-date, which is mechanical rather than a loss.
For accumulators, the drawback is friction: cash sits idle between the payment date and reinvestment, and reinvestment may carry a dealing charge. Over decades that drag is small but real.
Do not confuse a high distribution with a high return. Some funds pay distributions partly out of capital, which shows up as a high distribution-yield alongside a declining NAV. See return-of-capital.
Related: share-class, distribution-yield, return-of-capital, dividend, total-return