The WMR 196s don't have armrests fitted, The seats are similar/identical to those on the GreaterAnglia 745s minus the armrests.
Despite the higher overall capacity of the 196s over the 170s, I still think it was a little short-sighted of WMR to order 4 car sets as opposed to 5 cars. I'm not a user of the Hereford/Worcester services, Although having used the Telford/Shrewsbury services extensively, any time other than 9am-3pm, 4 car sets are often left with most seats taken, with the majority of evening/night services (particularly towards Shrewsbury from New Street) being completely rammed to breaking point, particularly on Fridays and Saturdays.
I think running them as 6 car (4+2) or 8 car (4+4) would be really beneficial for certain services, although I don't think they'd be clear for usage, and I think the only stations along the Shrewsbury line that could fit an 8 car unit are; Birmingham New Street*, Sandwell & Dudley, Wolverhampton, Telford Central, Wellington** and Shrewsbury, with Cosford possibly being able to handle 6 cars. As WMR services stop at most stations along the route (the ones not listed can only fit 4***), likelihood is that they wouldn't be able to run in longer formations, although TfW could if they wanted to (they certainly have the demand for it) as they only stop at principal stations.
(* Birmingham New Street Platform 4C could likely only handle 6 cars at most, so any 8 car services would have to use a different platform)
(** Wellington could comfortably fit 8 cars or more in the Westbound direction, Although the Eastbound platform is shorter, only just fitting 7/8 cars of a 10 coach 221. Wellington westbound and both directions on the rest of the stations on the list could easily fit 10/12 coaches)
(*** Bilbrook and Oakengates can currently only fit 3 coaches, although are in the process of being extended to handle 4)