^ I tend to agree. While the mystery of the Reapers and what happened to the Protheans was interesting in ME1 when it was new, the Reapers as an enemy were a huge problem. Of course they didn't have to worry about it in ME1 since you don't fight the Reapers. You fight the Geth, led by Saren. Sure, Saren is working for the Reapers and causing trouble in the Attican Traverse, but you don't have to fight the Reapers directly. One whole Reaper appears in the game and is killed indirectly. I also share the view that the retcon of how Sovereign was killed was disappointing. Ah well.
I don't find much issue with the main structure of ME2 when you ignore Arrival. At the ME1 the Reapers are presumably trapped in dark space. That what the entire final act is about, preventing their use of the Citadel relay and marooning them there with the help of Vigil. There was no way to know how long it would take for them to get to the Milky Way via their own FTL, and so I don't take issue with the central antagonist being Reaper proxies who were already in the galaxy. Especially since the actual enemy in ME1 were Reaper proxies. Saren and the Geth also had killed far fewer humans than the Collectors when you start your mission against him, and somehow people complain about ME2 not having a worthwhile objective. As far as you know the Reapers are trapped in dark space, but the Collectors are here, now, abducting entire colonies of humans. Sure the game could have been about any number of things, but it wasn't.
I also disagree with the notion that the "Reapers were basically here" at the end of ME2, pre Arrival. I wasn't on the writing team, but I seriously doubt they intended them to be close until they started outlining the plot for ME3. In fact look at the cinematic after the Suicide Mission. Does that look like they are close? If you said yes, I will give you some perspective.
Sovereign and Harbinger are about 2 kilometers long. The Milky Way is 9.5x10^17 kilometers across. Or about 500 quadrillion times larger than a Reaper. I have trouble reconciling the end cinematic with things like "close" or "doorstep." If they were close, we would either simply not see them if the camera is as far from the MWG as it appears, or the MWG would essentially not be visible on the whole if the camera were that close to the Reapers.
When they decided to retcon the end of ME1 and potentially the end of ME2 with ME3, they created their "bridge" DLC, which was Arrival. This was easily the weakest part of ME2, even weaker than the Lazarus Project, which actually could be fixed with basically one or two dialogue tweaks.
I always hesitate to lump in the Arrival plot conundrum with ME2's plot because it has absolutely nothing to do with ME2's plot and everything to do with ME3's. If you think it invalidates any part of the ME2 plot, then your logic also can be used to show that it invalidates ME1's plot as well.
I honestly don't think ME3 would have been any weaker if they would have simply found another group to serve as the Reaper's proxies in ME3, who were building a force to take the Citadel and activate the relay for them. And avoid the Reapers altogether. The Reapers have been built up as nearly unbeatable, if not individually certainly as a whole. The only reason anybody had a chance to beat them was because the Protheans were able to sabotage the Citadel and prevent them from showing up in the first place.
The funny thing is ME3 is practically like that anyway. Cerberus is the new Reaper proxy force, and you fight them more often than the "Reapers." They even have a fairly charismatic but indoctrinated leader named Saren, I mean Illusive Man. The Reapers fighting in the galaxy now and attacking Earth doesn't hardly change the game. You can almost argue the only reason they show up at the beginning was so they could create their gritty "war torn" atmosphere that they were set on.
Of course in game it gives you a reason to run around and put out little fires for various factions to get them on the anti-Reaper bandwagon. But it isn't like there couldn't have been other creative ways to have you solve the Council-Krogan or Quarian-Geth conflict.
One final thought since this is getting long. I am not sure how an extended LOTSB plot for ME2 would actually work out unless you completely retcon the Shadow Broker from ME1. To some extent they did that anyway, the whole "he's not a threat to anyone, at least not directly" or whatever line Anderson says. Just going after him because Liara wants revenge doesn't make much sense. The only thing I could think of that might be an interesting way to run with that plot would be to either make the Shadow Broker a Reaper, or maybe an AI that predates the Reapers.