I used to be around the Three Towns quite a bit, and was there a couple of years back.  I've been a bit dismayed at some of the buildings that have disappeared.

The main building I am curious about was the old Ardrossan Town station building, the old building that closed in the late 60's and was reopened as a builders merchants, NOT the platform with a bus shelter that was constructed after the electrification.

It has always struck me that the building was quite impressive, especially for a smaller town like Ardrossan.  Now I see it has been demolished and replaced with what I can only call a rather characterless modern red brick unit.

Does anyone have any idea why this was done?

By the way, first post here for a while.

Welcome back... we can wait

This is as much as there is in public, there might be more to be found if you scour the Three Towns web site, where numerous gems are hidden away (and stay that way as they're hard to find)...

(Location cited as NS 231 421). Ardrossan (Town) Station, rebuilt c. 1890 by the Glasgow and South-Western Rly. Formerly a 6-platform through and terminal station, with a bay platform at the north end. The main platforms are on the up platform in a 1- and 2-storey ashlar building.
J R Hume 1976.

This intermediate station on the Ardrossan Harbour branch of the Glasgow and South-Western Rly was opened (as Ardrossan Station) by the Ardrossan and Johnstone Rly in 1831. It was renamed Ard rossan Town Station on 2 March 1953 and closed to regular passenger traffic on 1 January 1968.
The new (British Rail) Ardrossan Town station was opened on the same site on 19 January 1987 and remains in regular passenger use.
Information from RCAHMS (RJC M), 9 June 1998.
R V J Butt 1968.

Unfortunately, there's no hints as to why the demolition and rebuild.

Maybe the root cause was our old friend "Health & Safety Reasons", and they couldn't make the old station and platforms comply with ever changing and increasing legislation economically, and it was cheaper to knock it all down and start again.