Let me begin by saying I will never be convinced to do anything simply because that is the way it has always been done... that is a lazy and indefensible argument - there needs to be a reasoning of why it should be done a certain way. Moreover, what is a standard genealogical practice may or may not best suit wikitree's needs.
With that said, I am actually somewhat ambivalent to the display of names on wikitree and can see specific benefits, justifications, and logic in different display formats.
The case I see for the current wikitree practice of displaying women with their 'married' names:
1. Wikitree (unlike standard genealogy) is trying to attract people using cousin bait, and tight integration into Google search results. Not just researchers, but anyone that could be a potential source who can add a personal memory about someone. They may not know standard genealogical practices, and they might only know their Great Aunt Mary by her married name. By using the names they were/are actually known by (whether that is a married name, a birth name, or some other name) increases the likeliehood that we will achieve this particular aim of wikitree.
2. Current Last Name, while it is greatly impacted by marriage, is not a married name field - it also includes adopted names, legal name changes, and names that change over a persons lifetime (for example translation/mutation as they move to a region with a different language) As above, this helps attract people who are non-researchers and may not know other names for the person; again while our focus is on genealogy we cannot lose sight of the fact that we are also trying to make it easy for family to connect.
3. As Kitty has already said, the Current Last Name should reflect how the person is addressed, or how they were addressed when they died - this allows for international differences of conventions (such as the oft-cited Acadians) as long as someone does not impose a current last name on a person who did not use that name. The onus is on the researcher/contributor to select the correct name. This naturally leads back to the other currently ongoing conversation on not auto-populating the current last name field for women on marriage, and I agree it should not be autopopulated as that 'imposes' a regional bias and 'removes' responsibility from an actual person.
Now the case In favour of the Genaealogy Standard:
1. A person can only be born with one name - every other name is 'transient' so using the birth name is the only 'constant' way to refer to a person. 'Limiting' to one name also makes 'cleaner' displays.
2. For many genealogists (amateur and professional) this is the way they are taught to do it, and the way they are accustomed to doing it; it is thus intuitive for many researcher that it should be displayed in the conventional way. It also agrees with much of the available literature on genealogical research. (English-speaking literature anyways) ***notice this is not an argument of 'because this is the way it is done' but 'this helps many people who are likely to become contributors use the system more easily'.
3. It is the format most removed from a regional bias as no matter where you are people are born under their birth name (I know that is a bit of a redundnacy to say but whatever...) however as Kitty also pointed out even the simple act of displaying first name before last reflects a regional bias so at some point any decision we make (within the current system capabilities) is going to contain some bias.
I am sure people can add endless arguments to both sides of this issue, but from the few arguments I make for each side I think the answer hinges on the question: Are we in this for ourselves (wikitree members, and genealogists) or for everyone (the general public of non-researchers).
Not to cop out, but as I said I am ambivalent to the issue and am not going to favour either case - my only concern is that we are not doing something just because that is the way it has always been done; by that argument wikitree should not exist and we should all be sitting in archives and libraries poring over microfilms - we must accept change when it improves desired outcomes and resist change for the sake of change.