This is the only easy answer you should give: “It’s not that simple.”
Most people want easy answers. They prefer you to simplify decisions and give them a clear
yes or no
buy it or don’t buy it
replace now or later
open source or commercial software
new or refurbished
Coke or Pepsi
The minute you take a complex answer and get pressured into simplifying your answer, you’re introducing risk into the equation. There’s a REASON it’s a complex answer.
If there’s a risk of a customer saying “but you said…” at ANY time in the future then you have your answer: don’t put yourself in that position.
“Doctor, will this operation save their life?” – it would be hard to find a doctor that will give you a definitive yes. Instead, they have to give you a long list of caveats and explanations of why it’s not that simple. Your professional service is likely no different.
When someone asks you for a simple answer to a complex issue (and it’s probably complex if you’re involved), reply with “I wish it were that simple” and then respectfully find out how much time and/or interest they have in more background information. Some people will want to know the details even though they may be technically unprepared or unequipped. Others will not want to know and will be ok with “it’s not that simple.”
Note: be delicate. If there is risk involved (data loss, etc) then the request for a simple answer may be under duress. So while you may find it annoying that you’re being pressed for a guess or an oversimplification, it’s likely not because they are trivializing your job. It’s extremely easy to appear condescending, difficult, stubborn. Hopefully you’ll come across as conservative, which in the long run your customers will appreciate.