I think the biggest issue is expectations: one team will always create the better car. It's what competition leads to. So however you turn it, one will have the advantage. Often that advantage is big enough to be dominating from the first to the last race, like the Schumacher-Ferrari era, the Senna-Prost era and the Vettel-Red Bull era. So you can't realistically expect to have 8 drivers go into the last round with a shot on the WDC.
Some years have a higher competition. Those are rather rare; the last one was 2010, with 4 drivers going into the last round with a shot at the WDC.
However, the most likely scenario we have in F1 is one dominant driver in one dominant car. Schumacher proved that, Vettel did so too. This year I like to say it was even between Rosberg and Hamilton, and imo we should be greatful for that. It was, in my eyes, a very good season. Last year we knew that Vettel had it in the bag just over halfway the season. Was that fun? No, completely not.