Do you have confirmation on this?
Su-25 does not use targeting pod because it has a laser guidance system (SVP-24) built in at its nose, just like Jaguar strike jet. SU-24 is also equiped with SVP-24 built in, so it also does not need targeting pod.
Also, SU-34 has Platan targeting system built in.
My speculation is that they were carrying dumb iron bombs, and need to flow low to drop the bombs as accurate as possible to avoid collateral damages. This may also indicate low inventory level of precision guided missiles/bombs in Russian airforce, and the need for allocating usage of PGM for high valuable targets only.