Why does the UK Parliament still prohibit members from resigning?

Question

Under a Resolution of the House of 2 March 1624, Members of Parliament cannot directly resign their seat. Death, disqualification and expulsion are the only means by which a Member's seat may be vacated during the lifetime of a Parliament. Therefore a Member wishing to resign has to go through the process of applying for a paid office of the Crown, which automatically disqualifies the Member from holding a seat in the House of Commons. There are two such offices: Crown Steward and Bailiff of the Chiltern Hundreds and of the Manor of Northstead.

Source: House of Commons Information Office: The Chiltern Hundreds (PDF)

Perhaps there were good reasons to prohibit members from resigning in 1624. But in the past 200 years, what has been the rationale to retain the system where MPs are not allowed to resign, in particular since they can de facto resign by applying to be Steward of the Chiltern Hundreds?

Answer 1

In a sense, your question contradicts itself. First you say that MPs aren't allowed to resign, and then describe a procedure through which MPs can resign :-)

Drafting a law costs time and money, as does passing them through the parliament (which will probably include some bikeshedding about it), training civil servants, modifying computer systems, etc.
And what does it accomplish, really? Make a very specific little-used well-understood part of the law a bit prettier?

How will it advantage an MP? How many extra voters will the MP attract? Is there a possibility it can be seen as elitist navel-gazing by voters?

Yes, it's a somewhat convoluted procedure; but it works, so why fix it if it ain't broke?

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As a matter of interest, the law exists in the first place because:

It should be remembered that in those days serving in Parliament was often regarded as an obligation to be accepted only reluctantly rather than an honour to be eagerly sought. Voluntary relinquishment of a seat was not, therefore, something to be encouraged. It was also the case that, before the sixteenth century, it was very rare for a parliament to sit for longer than a few weeks so that a procedure for resignation was hardly necessary.

Source for that. It also tells us why the "paid office of the Crown"-law clause exists:

This was because it was assumed that a Member receiving a salary from the Crown could not be expected to scrutinise the actions of the Crown or the Crown's government.