While they cost less to run than the cost of a new one it makes sense to keep.
I have just had a new one on a 4 year lease as my last one, which was all paid for, started playing up with non-starting and big repair bills which was costing me in time, lost earnings and repair bills, so I had rid.
Will have a new one agian when this lease runs out, that way I always (hopefully!!) have a reliable van.