If it's important to the sound of the song (for example when playing certain rock/blues/metal styles) then I tune my strings to match the guitarist. This turns the bass into a "transposing" instrument and when communicating between band members, we still call the strings E, A, D, G (even though they are actually concert-pitch Eb, Ab, Db, Gb).
On the other hand, if having the lower-octave Eb is not important to the sound of the song (for example playing jazz standards in the key of Eb with saxophone and piano) then I stay in standard tuning.
There is NO CORRELATION between a musician's skill level and whether or not they choose alternate tunings. Some of the best-of-the-best musicians of all time (like Jaco Pastorius, Jimi Hendrix, Michael Manring, Joni Mitchell, SRV, J.S. Bach, etc.) have experimented with non-standard tunings. Alternate tunings, drop tunings, and capos are not a "crutch" as some would have you believe.