The roamer is mostly like a Chevy Suburban or Tahoe, with a V8. It would be nice to have a V6 option, to make it more of a crossover.
The Roamer is most like the Ford Explorer (although they are based on a medium and light truck respectively), which is much smaller than a Suburban (based on a full size truck). The 1995 Explorer was only offered with V6 or V8, but straight 6 engines were still around in the late 90's. For example, the Jeep Cherokee was offered with a 4.0 i6 for ages. I don't see a reason to give the Roamer an official V6, the i6 works fine and makes sense.
Difference between i6 and V6: i6 - All cylinders are in a row, from front to back of engine bay. V6 - 3 Cylinders on one side, 3 on the other pointing a 45-65 Degree angle, both sides front to back. There more differences. V6 is usually more "unbalanced" while i6 keeps weight reduction and balance better. V6 produces more power. i6 is meant for old pickup trucks, and is less popular, as the popularity of V6 increases fast. Besides, you would never see a i8 or i12 on the road. i4 might turn into V4 soon though.... the letter V is better.
The letter V increases production costs, maintenance costs and complexity. Inline engines are more reliable generally speaking because they are a simpler design: 1 cylinder head and gasket instead of 2, 1 exhaust header instead of 2, etc. The only thing making a V6 the more popular option is packaging, it's much easier to fit a V6 engine in a short engine bay because it's only as long as an inline 4. V4 engines won't be coming any time soon, for the reasons stated above: higher cost, higher complexity, and higher weight.
I'm speaking in general terms. BMW engines are never simple, of course a honda v6 from 1990, for example, is simpler than a BMW I6 from 2017. However, if you compare a generic I6 with a generic V6 the I6 is always simpler and cheaper.
I like the idea. I've always thought of the roamer to be closer to a Nissan Xterra than a Tahoe, and the Xterras got a V6 option and an I4.
Also, truck-based SUVs usually have I6s designed for trucks. The Chevrolet Tahoe had the Chevy truck 4.1, on which the in-game 4.1 is based. In a similar manner, the TrailBlazer had a Vortec 4200. --- Post updated --- The Roamer is closer to the Tahoe in size, and there were no 90s Xterras, but there were 90s Tahoes.