Its not so much the lack of efficiency, but rather the high cost, that makes PV solar uneconomical.
Abosolutly, sunlight costs nothing therefore it does not matter if it is used inefficiently.
What does does matter is how much power is produced for a given investment.Therefore a reduced cost per watt is desirable, not a higher % efficiency.
Efficiency only matters if limited space is available, in most cases though the limiting factor is not roof, or other space, but money.