Is it necessary in todays environment?
Not sure what's being implied by
"todays" environment. Sandboxing has been necessary ever since malware was invented.
Is it no more than an overreaction to some imaginary threat?
There are many real threats already in existence (and many vulnerable users to go along with them).
Or is Apple being realistically visionary and conducting a pre-emptive strike against an amorphous, but nonetheless real, future threat?
Nothing visionary about sandboxing today... i think it's already been around a while.
What matters (to me) is the degree of control they provide the end-user. E.g., the version of TextWrangler we get at the MAS is crippled (can't edit system files). Fortunately, we can get a 'normal' version directly from Barebones. If sandboxing gets implemented such that even the direct-download version is
irretrievably crippled, then i won't be a happy camper.
