IMO, all of the subsequent reasons you listed played a part. There's no one silver bullet to explain why people bounced off of 4e. There were multiple issues, any one of which might have been possible to mitigate, but which altogether hindered 4e like a 4e monster festooned with conditions.
To whit, one reason that I don't think has been examined very much was that 4e was not blessed with a viable on-ramp. This had been called out by Mearls either before or during the D&D Next playtest. Their market research showed that many people bought the 4e Starter Sets, but did not move on to buying the PHB. That was part of the impetus for Essentials (with a revised Starter Set), as well as a design goal for D&D Next.
The original "Starter Set" was Keep on the Shadowfell. It contained quickstart rules for players, the adventure book for DMs, pregens, and battlemaps. What did it not have? Dice or tokens. And the quickstart rules devoted half a page (1 column) to discussing what a RPG was before then diving into 15 pages of rule explanations. I'm not saying that one couldn't pick this up without any RPG experience and get into D&D. I'm sure there are some who did. But they didn't make it easy. KotS and the quickstart rules are rather obviously intended to get already active D&D players quickly up and playing 4e.
The original "blue box" starter set is, IMO, not much of an improvement. The player's booklet is essentially the same quickstart rules as above, but at least time they include dice and tokens. The DM's booklet comes with all the necessary rules for DMs to build encounters. But the "introductory adventure" consists of...three dungeon encounters. None of which utilize the Skill Challenge rules. So you're not inspiring players, and not really giving them a taste of what a role-playing game can be. You're basically just hoping that they get hooked by the combat rules.
The "red box" starter set is a much better attempt. Dice, tokens, maps, power cards. You've got the solo tutorial, which is excellent. Unlike Mentzer Basic, you can choose from any of the major classes, and it gets across the rules the player needs to know while also getting them into character. All the rules nitty-gritty is in the DM's booklet, along with a proper introductory adventure. All leading to either the Essentials books or the original PHB(s). I think if 4e had led with this, it would have had a much better time. Alas, it was released in September of 2010. In January of 2012, a mere 15 months later, D&D Next was announced.