Other than education, what professional fields require their practitioners to compose a personal philosophy?

Are accountants required to compose their own personal philosophy of accounting? What about a personal philosophy of nursing for nurses? or lawyers? physicians? physicists? economists? astronauts? Google the term "personal educational philosophy." Read some of the hits. These documents range from the insipid to the inane. What is the practical, professional value of this exercise? What makes educators so unique that they each need their own personal philosophy of education while other professions manage quite well without them? ( I should mention that the recommended length for this document is "not more than 2 pages" ! ) Doesn't this exercise turn philosophy into a term or field of study that becomes so relative as to be meaningless? Doesn't this weaken educators' standing in academic and professional communities instead of strengthening it?

Umm... what?

The purpose of the personal "philosophy" in the interview process to becoming a teacher is at least two-fold. Obviously it communicates to your prospective school of employment what you think of yourself, your potential, your career, your plans, etc... But it also communicates these things to YOU.
YOU clearly and undeniably have these things in mind about YOU which gives YOU focus and clarity.

In my opinion focus and clarity are good things.

You are confusing yourself. The personal "philosophy" of a teacher can do as much harm to the field of Philosophy as a bird can do to the sky.

And yes, Philosophy is already relative. That's precisely its strength and beauty.

I actually drive people nuts by asking them to explain their personal philosophy as it relates to their work. My doctor, vet, massage therapist, shrink, guru, personal chef, etc...
It informs me how committed they are about their work and if they have a depth to their work or if they are merely making a buck. I generally figure that those who take the time to develop a deeper understanding of what they do and why will do a better job. Not always true but I think it increases the odds.
Personally I have found it to be a great tool for identifying areas I need to strengthen in my own work. I find myself in ruts some times and need to delve a little deeper to inspire new growth and development.
It can be difficult to develop but I encourage you to take the time and effort to create a philosophical statement that describes your intent and dedication.

Good Luck
ZebraFoxFire