Well-put! I think that for many frequent flyers though, they already have a strategy in place to deal with the dilemma in question. If one frequently flies and the company pays for it, then it would make sense to purchase the most expensive tickets the company allows, and do a cabin upgrade using miles. If paying privately out of one's own pocket, then the passenger has to calculate to see which tier they can reach.

Most FFPs do not allow roll-over status points (unlike Flying Blue). Thus, if one reaches the highest possible tier for their flying plans for that given year, then anything flying left over can be purchased with miles (since they won't reach the next tier anyhow).

Just my 2 cents. Obviously everyone's situation is different.