Compelled? LoL... NO.
If I like a model it'll stay in use until
A) GW makes a version of it that I like better, or
B) I die.
For ex: In
40k I have models
in active use that date back to the
RT days. And for
WHFB/Sigmar/Old World? Some of my Dwarves pre-date slotta bases!
I don't even feel compelled to re-base things most of the time. (I'm not re-basing long finished models with out damned good reason.
GW farting is not a damned good reason. What you all do in your tourneys is also not a good reason))
Best ex is the Bloodthirster bought around 89'/90 that's now
smaller than a current Demon Prince. "Tiny", as some of my opponents have dubbed him, is still played as the Bloodthirster he was bought as.

Between decades of
WHFB &
40k play he has 10's of thousands of pts worth of kills. He is NOT going to be dishonored by being demoted to Prince status because he's smaller than another model. The only changes to him over the years have been two better quality paint jobs & about 10 years back I replaced his original 40mm(??) square base with a 2" square resin cast base covered in skulls. Maybe one of these days I'll have one of the kids at the shop print me a 60mm round (dreadnought size) skull covered base.... (Bigger than about 60/65mm will just look stupid from a modeling perspective
IMO.)
Want to? Sometimes. It depends upon the model.
Usually it's simply because I like the new model more than the previous.
Examples of (
40k) models that I've replaced:
*Necron Destroyers - have you
seen an original destroyer??
*Necron Wraiths - A) looks better than the 3e version, B) the 3es were incredibly fragile & top heavy
*Tau stealth suits
*Tau Broadsides
*Eldar 2e metal Swooping Hawks - beautiful sculpts. AND no longer top heavy even on larger/weighted bases!
*
CSM Raptors - never really liked the actual Raptors. Finally replaced with the brand new 30k assault Marines w. jump packs.
*Chaos spawn - just about anything looks better than the poo
GW wants to sell you for this unit. Me, I'm using D&D Otyogs (sp?).
*Khorne Juggernauts - modern metals/plastics far better looking than the old 2e eras
*
SM drop pods - went from old Armourcast resin to
GW (4e?) plastic version. Mostly just an issue of practicality - the
ACs were heavy & took up alot of space transport wise (I had 9 of the things). They also had
sharp edges (even after sanding - they could've doubled as giant shuriken...) The plastic ones were just so much easier to carry around.
*Necron Monolith - stupid price, but a waaay better model.
*coming soon: Nightbringer (& hopefully Deciever??)