I've got no problem with people making money for the work they do, but especially when those people are legislating for the masses they have to apply the models of the rules they set and not be the exemption.
A good example of a public-sector allowances system is the one used by the armed forces, who are provided with accommodation, normally relatively cheaply, which they occupy when in the role they are employed for, but who must return it when their job changes. The trimmed down military allowances system is now frugal, but generally speaking repays people for legitimate costs, and matches the need for universal public sector frugality. So accepting there will be differences, what is wrong with the same principles being applied MPs?
The road to revolution is paved with examples of appointed leaders imposing 'do what I say, not what I do'.