A lot of reasons to get a McGizmo.
I'll try to give a reason not to buy one.
They are obviously great lights but just to balance all the pros...
This is sort of the same question or answer as:
Why should I pay $15 for a Mag when this $5 multiled light works for me?
Why should I pay $50-70 for a Fenix etc when this $15 Mag works for me?
Why should I pay $100-200 for a Surefire/HDS when this $50 Fenix works for me?
Why should I pay $500 for a McGizmo when this $150 Surefire works for me?
The more expensive light may be:
better quality/lifetime
more reliable in critical situations
better warranty
higher output / better beam / better tint
better/more sofisticated UI
better ergonomics
better looks / style ...
For me those $5 lights is enough for 90% of my needs I think. (But I don't use any of those lights)
The rest (Fenix, Zebra and similar and some Surefires) covers all my needs.
Well, it's a little bit more than I need actually but I like them.
I have thought about getting a McGizmo but realized that it would only be a shelfqueen for me and I don't want that.
For me it's to big to EDC (I prefer AAA) and as I understand it, but I might be wrong, it's not the UI I want.
Then just being interested in nice lights might make it worth buying even if you don't need it.
A reason as good as any!