Platform singular - the 'London bound' platform is still there, although not sure whether it's in a suitable condition for passenger use by current standards; the 'Exeter bound' platform on the loop is long since gone.
There has been a campaign for many, many years to get the station reopened - I was involved in it until I moved away in the late 90's as I lived a mile or so from the station.
Local councillor Andrew Turpin is very keen to see it reopened - http://www.thisisthewestcountry.co.uk/news/somerset_news/7991036.Campaigners_defiant_over_Chard_Junction_sale/?ref=rss but that's the last news I can find about it.
The station itself is about a mile from the main village of Tatworth/South Chard, and three miles from Chard itself (the Chard to Taunton branch of course long since gone and built over in a number of places) so you'd need about a 4 mile bus journey to get into Chard - whereas both Axminster and Crewkerne are only about 8 miles away.
You're right it does seem silly when a large number of trains have to stop there to wait in the loop for a passing service anyway, but I guess that it's more down to the bean counters than anything else.
Within 5 miles of Chard Junction you have a population of about 18,000, and the alternatives of Crewkerne or Axminster on the same line, or Taunton on the Paddington line being about 15 miles away, there is certainly a good potential - but I wonder whether the thought is that taking those people that would use the train away from Axminster or Crewkerne would make either of those stations less financially viable?
I totally agree with there being no need for more work (on the face of it) than tidying up the platform, installing a shelter or two, and tying in with the local bus service to make everything work together - although admittedly the cost of reinstalling the second platform could be quite an expensive task. I believe that some of the land of the old platform may well have been 'commandeered' by the adjacent milk factory (which although still rail connected hasn't seen any milk trains for about 30 years and I'm not sure quite how functional the facilities still are).
Crewkerne's second platform still exists and appears in reasonable condition, but when I was there about a month ago there didn't look to me like there was enough room now to put in a second track and that's without all the clutter such as control boxes that are in the space..
It's about an additional 5 minutes on the train from Chard Junction to Axminster, then about 35 minutes on the bus from Axminster to Chard. Unless buses were timed to meet the train then I suspect that the 20 minutes it is likely to take on the journey from Chard Junction to Chard on a bus, you're only saving around 20 minutes each way on the journey. To local people that would be a significant change, possibly opening up employment opportunities, although in all honesty I wouldn't fancy the commute from there to London!