Add Shear and Taper to Transform Effect (or add as Warp effect)
Shearing and tapering are ones of few operations that can't be automated procedurally.
Using 'Free distort' is very inconvenient, because it works in small dialogue window that doesn't show actual artwork (it doesn't even have Preview tick! — I'll add another feature request about it). Although 'Stylism' plugin from AstuteGraphics solves problem with control, revision is definitely required.
Shear tool and Free distort tool are fine, but they are live tools, and won't help to repeat same the effect later if needed.
Please, add shearing and tapering either as part of Transform effect or new Warp (both as effect and envelope preset).
A Shear can be calculated with a rotation and scale, we know. There is even a script to do that, http://sysys.blog.shinobi.jp/Entry/53/
But we still need is a separate thing!
Sapan Giri commented
Yes definitely this will help retain the original artwork whilst able to transform. Especially this will help generate the Isometric Objects once object styles are defined using such Effect > Transform.