yes I agree with you ... these are valid points and sorento doesnt come close to fortuner when doing proper offroading but not everyone buys fortuner for offroading.
The things that can make sorento popular are:
price (which should be lower then fortuner in any case) and it will be considering its old gen and also how lucky group priced sportage.
comfort; sorento has multilink suspension and according to reviewers it has one of the best seats in all 7 seater SUVs (fortuner doesnt come close to this)
Power; sorento will be the only option offering 3,3L V6 (295 hp) and even the lower 2.4L is better than 2.7L of fortuner.
Features: It will have panroof, auto dimming mirrors, dual electric seats, list goes on and on.