Is there anything specific to a strat that lends itself to this tuning?

I'm going to say no.

Other Answer's have pointed out that this tuning is used by many artists who are not Stratocaster guys. As for why SRV and Jimi Hendrix played that way, it's hard to say.
I think it's a safe to guess that SRV preferred really heavy strings for their sound, and downtuning made it easier on his fingers.
I've heard somewhere (I wish I could back this up) that Jimi's time as an axe-for-hire meant he played with alot of horn bands, where keys like Eb, Ab, Bb were more common. A guitar in Eb standard tuning has convenient open chords in Eb and Ab (not so sure about Bb). Another reason is that Jimi's voice was more comfortable in Eb.

Is there anything specific to a strat that lends itself to this tuning?

I'm going to say no.

Other Answers have pointed out that this tuning is used by many artists who are not Stratocaster guys. As for why SRV and Jimi Hendrix played that way, it's hard to say.
I think it's a safe to guess that SRV preferred really heavy strings for their sound, and downtuning made it easier on his fingers.
I've heard somewhere (I wish I could back this up) that Jimi's time as an axe-for-hire meant he played with alot of horn bands, where keys like Eb, Ab, Bb were more common. A guitar in Eb standard tuning has convenient open chords in Eb and Ab (not so sure about Bb). Another reason is that Jimi's voice was more comfortable in Eb.