You can just read the wiki and learn each ability’s range. For example:
Tiered quivers have a range of 15 tiles from the user.
Tiered spell shots have a range of 16 tiles from the point of target
and your example, gcookie, has a radius of 4.5 tiles that increases by 2% for every WIS point above 50, as does every other tiered seal.
I don’t see why this would be particularly useful, especially considering that most if not all abilities list their working radius or range, as shown below (I also happen to have a gcookie on a pally with 75 WIS so this is a perfect comp). The only thing is that often times it’s listed as squares rather than tiles (they’re the same exact metric).
Also consider that there’s graphics that roughly show the range of your radial abilities. You can see this in-game whenever you use your ability, even with disable particles master turned on as well as particle effects turned to low.
While we’re on the subject of knowing certain ability aspects, here’s a good point to consider. There are some abilities that don’t list ranges in certain aspects. For instance, teleporting abilities don’t list the maximum range (if I remember correctly, it’s a limit of 13 tiles), and scepters don’t list the range of which the initial target can be hit (I don’t know this off the top of my head). This goes for weapons as well. Wouldn’t it be nice to see a little tooltip for wavy shots or parametric shots? Or how about projectile speed? When Deca added the wakizashi ability, they definitely gave us enough information as to the cast range and the projectile range of the ability projectiles, which is a nice touch. Hopefully we’ll see more information (or at least the option to see thereto) as to the currently behind the scenes aspects of not only abilities, but other equipment as well. So to summarize, they don’t need more meaningless graphics depicting something we know already. They should instead make it so we’re able to see more info on a weapon, on the fly, from the tooltips.