What kind of guidance does it use to achieve 40m CEP? From the picture, the shell does not seem to have a homing seeker, so the 40m CEP is likely based on inertial navigation or GPS, which is pretty respectable.
If the shell is using IN or GPS to keep costs down, it can quite easily be upgraded with a laser homing warhead for single digit CEP, but that will raise the unit cost of the shells, and also would require someone on the ground near the target lasing it to achieve the best CEP. But it is not always possible to have SF units on hand to laser tag targets, and in a lot of causes, such extreme precision isn't really needed.
The main aim of this shell is to extended the effective range of the artillery piece to between double to triple the range typical 155mm artillery can achieve with conventional shells or even rocket assisted shells.
The control fins are necessary to correct for wind and other external factors as well as the inherent limitations of the canon itself to achieve useable CEPs at such extreme ranges, but the shell itself is not designed as a PGM to keep unit costs down.