I guess we disagree on one important aspect. I don't believe a progress path consisting of only LFR content is good for anyone playing this game in the long term, no matter how casual you are. The fact blizzard tries to stimulate players to look around for a bit and maiby consider doing some normal raids, some dailies, or some dungeons, instead of hitting that 'LFR que' button week in week out is good for these players in the long term.
You are 100% correct in what you set out to achieve but along with Blizzard you are dangerously wrong in the way in which you want to achieve it.Lets look at how you are correct first:
From a players perspective it is good to have a variety of fun activities that you can pick and choose from in accordance with the amount of free time you have or your tastes.
From Blizzards perspective it can also be good. The guy doing only RF is liable to quit if he grows bored of RF or if Blizzard release a weak tier etc. So greater variety leads to more resilient subscriptions and you attract more potential customers with different tastes.Now let's look at where you and Blizzard are frighteningly wrong:
You propose using an arbitrary ilevel restriction to bar players from using the one piece of content they do like in an attempt at “forcing” them to do content that they either lack the time to complete or that they dislike because it is not fun or they aren't interested in it.
So let's break that down further:
If a player doesn't have time to complete the optional content, by forcing them to complete it in order to access the content they do want to play, you merely force them to quit the game. They are no longer able to access and complete anything that interests them.
If a player dislikes the content (if they liked it they would already be doing it) then by forcing them to complete bad content in order to access the content they do like, you again risk forcing them to quit. They will weigh up how much they like their favourite content against how much the dislike the mandatory pre-requisites and conclude that on balance it isn't fun or worth it any more. Now let's look at how you should achieve your goal:
The correct solution is to improve the “optional” activities or their rewards so that players do them voluntary and not because those badly designed activities are blocking access to their favourite content.
Take daily quests for example. These are incredibly unpopular and as the CRZ fiasco has shown players hate the dated mob tapping design in WoW that makes the questing more of a free for all PVP experience than the cooperative PVE experience they signed up for. I have only just started enjoying dailies now that most of the other players who ruined the experience have disappeared. I run them for the lucky coins and VP which are a good incentive if the content wasn't so irritating in the first place.
If Blizzard took a leaf out of GW2's book and solved the mob tapping issue and also removed some of the other problems (too many Klaxxi and GL dailies) and perhaps improved the rewards they would have had less complaints and more players voluntarily running and enjoying the content.
You can apply much the same rules to Dungeons, Scenarios, Pet Battles and farming etc. Look at why some/lots of players refuse to do them, ask yourself is it because it isn't fun or is it because it isn't rewarding. Then fix it so that they want to do it.
Do not leave sucky content unchanged and merely force players to run it by making it compulsory in order to gain access to the good stuff. Fix it and make them want to do it because it is good in its own right!