politeness and quizzical questions

Writing an email for work today, I found myself adding
those polite little "I'm not saying you're *wrong*,
just trying to clarify and discuss" phrases.

For example, on a descending scale of "likely to
trigger a defensive response":

1. Why the <bleep> are you doing it that way?
2. Why are you doing it that way?
3. Out of curiosity, why are you doing it that way?

I wanted to write #1, first wrote #2, and changed it
to #3. Speaking, I could say #2 with a quizzical tone
and look and it would equal #3.

Then, it being a rather dull Monday at work, I started
thinking about conlangs...

How do you do it? Mine doesn't have anything in
particular yet, but... Maybe a quizzical mood? Or
particle? Some form of subjunctive might work. Phrases
like English uses? Some languages have a fairly
extensive hierarchy of politeness, which could
function this way.

Right now, tongue only partly in cheek, I'm tempted to
add a "tactful mood". Nice, succinct translations...
;-) Like this, for English, since my conlang things
aren't with me.

Say, "-lis" for "I'm being tactful right now".

Out of curiosity, and please don't get defensive on
me, but why are you doing this?
Why arelis you doing this?

With all due respect, why the <bleep> are you doing
this?
Why the <bleep> arelis you doing this? (for a given
value of "tact", and probably recieved just like the
"original" would be...)

We should do it this way.
We should do it this way.

Well, I'm not sure, but maybe we should do it this
way.
We shouldlis do it this way.