That's clearly your decision as a customer and one that I may also make.
What I am trying to explain is the carrier’s reasons for the decision to limit luggage.
The fact they don't accept as much as 20kg is not because they are "crap."
Decision based on operating costs.
Passengers seem to have an unrealistic view and expectations what they should expect from a low cost carrier.
If you pay less you get less.
The bottom line is the more the carrier gives in service the more this costs or the less profit generated for the carrier.
but you didn't answer my question in terms of pounds shillings and pence.
This is a good question to ask. It is difficult to answer in a general case.
If the carrier is able to carry lower price fuel and ferry it for the return journey this will reduce operating costs. Clearly this depends on the actual prices in use.
The extra cargo which can be carried instead of the extra baggage weight the revenue from this will depend on the type of cargo being carried for example.
Low Costs, Remaining Profitable, On-time performance and Safety are all top priorities for low cost carriers. Customer service clearly comes below these with many of the low costs. Bottom line is customers are cost driven.
Jonathan