It takes actually for a casual player a week and a half finishing the ARR and another 2 week to finish HW content, if played at a rate of 4 hours a day, I've tested it. If you have more time then that, well you are looking at 4 days of 1-50, 2 days of patch 2.0 - 2.55 (entering ishgard), 5 days to get through the whole HW expansion including the up to date patches.
Will you have to skip most of the game to archive that? Sure but it's possible, therefore most of the wow players as you call them, are joining because their friends are at end level, meaning they have read plenty of guides and are only interested in skipping content. These people also do not fall under the category of casuals.
I think you're throwing some groups all together and putting them in the same stereotypical drawer. Casuals, do take their time but it don't matter to them. They are enjoying the game by itself and are in no rush of reaching end game as quick as possible.
With that out of the way, you could always wait for the new expansion in June, apparently you'll be able to skip the old ARR main story content if you are willing to pay via mog station.
SE has shorten most of the main scenario quests, removed quests that were MSQ prior and put em as side quest that are not mandatory anymore and increased the exp etc. It took us 2+ years to go through the same content, players nowadays be able to skip and reach within days.
While I think we should have added this potion way earlier, especially for people that like their alts, I don't think we need to remove half of the actual base game, just that people can reach HW content within a couple of hours or days. That kinda beats the purpose of a game that's very story driven.
Let me add, even if you are making it too the "end" within a short time, one thing SE didn't do, give out gear. I know people are joking around saying we having free gear etc, and while it's easier to obtain than to old ARR times, it's still hell of a farm. Plan another 3-4 months till you actually have the full set of gear that your class needs, just to find out that with the release of storm blood, that gear becomes meaning less. You will have not only to start leveling your way up too 70, but will spend the next year or two (depending when 5.0 comes out) running after gear that's renewed every 3 - 6 months. A never ending cycle!
If you're not up for that kind of "challenge" might as well not continue with the game because there's no change on the horizon anytime soon lol.