Focus on second-to-second play first. Nail it. Move on to minute-to-minute, then session-to-session, then day-to-day, then month-to-month (and so on). If your second-to-second play doesn’t work, nothing else matters. Along these lines, if your day-to-day fails, no one will care about month-to-month, either.
If you want to review a game completely you have to test every aspect of it. In the case of Rift that includes all dungeons, quests, tutorial, raiding, BG-PvP, open-PvP, etc. That doesn't mean however, that you are not allowed to have an opinion before you tested it completely. If the first 10 hours weren't fun, that is certainly valid and interesting information. It just isn't a complete review. In Tobold's case that is perfectly alright. He isn't a professional game tester, after all; he's a blogger.
Now, you should be a bit careful about a final score, of course. Saying that you tested a game for some hours and claiming that it isn't fun (I am talking abstract now) is not acceptable. What you can say is that the aspects you tested weren't fun (for you, but that's obvious).
About Brenda's quote. It doesn't apply to this situation. Brenda gives an advice to developers. She knows that players stop playing very fast if a game isn't fun on even very short time scales. That is the reason for rogue-likes being so unpopular today. They are still a hell of a lot of fun once you managed to get into them. But to get into them is really hard, because the graphics are so much worse than what we are used to.
The quote cannot be used as justification to not test a game for longer than a few minutes. As a developer you have to fear that if your game is not fun for the first 10 minutes, players stop playing forever. As a player, however, you have to fear that you quit a game after 10 minutes, although it could have offered hundreds of hours of fun once you have played for 10 hours. And this is exactly the kind of information I want the tester to give me: Should I invest a lot of time, because the game becomes really, really fun later on?
Moreover, don't interpret Brenda's quote in a way that every single individual, isolated activity has to be fun. Fun Fallacy, you remember? Millions of players got to level 60 in classic WoW, because the second-to-second and minute-to-minute gameplay was fun. However, it wasn't fun if you looked at it isolated from the rest of the game.
If you, as a developer, had employed some testers and given them the second-to-second gameplay without a world, without talent trees, without other players. Just the pure, isolated, immediate gameplay and if you had asked them whether they looked forward to do this for 300 hours /played...
Well, you get the point. The second-to-second gameplay has to be fun, but must not be looked at isolated from the rest of the game. The fact that you can explore a world, access higher levels, explore your character's abilities, meet other people and, yes, even gain equipment, is essential.
Humans like to invest much more than to they like to consume. The feeling of building / creating something is the most powerful incentive in MMORPGs. It gives the game more (subjective) meaning than single-player games. The anticipation of future fun is fun in itself.
In no way should the quote be used to design games as a chain of seperate, inherently fun pieces. Take the WoW-LFD. Even if you ignore the social consequences of the anonymity and the immersion-breaking teleports, the LFD has a fundamental problem: It is just too much candy all at once. Dungeons in WoW are (were?) fun; unless you run 10 of them in a row - or one every day. By cutting out the supposedly unfun elements, Blizzard allowed the player to get as much candy as he wants whenever he wants. This leads to players grabbing as much as they can and then throw up.
Just like cooking is fun due to the pleasant anticipation of eating, the dungeons were fun, because you looked forward to do them. It is the same with shopping: Buying the 20.000 € kitchen in itself is not fun. The pleasant anticipation (of showing it off ?) is.
We need some time between fun events to appreciate them. Chrismas every day is not fun. Chrismas every 365 days, is. For most people, Christmas is also the perfect example for anticipation of an event being much more fun than the event itself.
Pacing of fun events and variety make a fun game. Even the most fun thing in the world becomes tedious and boring if you do it again and again in short succession. Developers should not trust players to know this or even hold themselves back. (They certainly should not offer cookies for chain-eating other cookies!) It is the developer's responsibility to create a fun game, not the player's responsibility to play it in a way that is fun. At least, for your own sake, that is the point of view you should assume as a developer.