I hate to say it but dissolving LMP1 makes some sort of sense in a series like ALMS. The big factory teams don't race in the series and if...
In a way, it does, yes. But it also has to be understood that the ALMS has been a battleground over the years, between LMP1, LMP2, the manufacturers, big name sponsors, and the ACO. And Scott Atherton and Co., have been caught in a rather unenviable position over the years.
When Audi Sport NA joined the ALMS in 2000, it was a huge boon to the series. Along with BMW, they brought with them, the panache of a major manufacturer and the Le Mans winner. As a result, the series gained both notoriety and credability. Not to mention a financial boost as Audi soon became the title sponsor.
Audi continued to keep a presence in the ALMS, and privateers like Champion Racing, who campaigned an R8 for two seasons, continued to enjoy factory support and the series continued to prosper. But in 2006, things changed. Audi began running the Diesel powered R10 and Penske racing entered the LMP2 class with the new Porsche Spyder Prototype. Due to the nature of some of the ALMS tracks and the length of the races (ergo fuel stop and pitstop rotation), Penske sometimes found themselves in the unexpected position of competing for the outright victory. Naturally it didn't sit well with Audi that LMP2 cars were making their new Diesel, Le Mans winning R10 look decidedly ordinary. But that's the nature of racing.
Others took notice and in 2007 & 2008 there were a stream of newcomers in the LMP2 class, including some big names in American racing, such as De Ferran Motorsports, Andretti Green & Fernandez Racing, all hoping to capitalize on the situation and fight for the outright win. And more often than not, they did just that. Those teams also brought with them a level of competition and professionalism that some of the series regulars weren't expecting. It was an exciting time and a great two seasons of racing, with a lot of open wheel regulars suddenly racing LMP cars.
But it wasn't a love fest all around. Especially not for Audi, the series title sponsor. I would have to go back and check specifics, but at some point between 2006 & 2008, the rules for LMP2 cars differed between the ACO and the ALMS. LMP2 was enjoying an amazing resurgence in the ALMS and the LMP2 teams were quite happy that they were running with more power then they could under the ACO rules and the exposure it brought them. Audi obviously wasn't and claimed foul. They had threatened to quit for two years running and in 2009, they did just that, essentially picking up their ball (and sponsorship money) and going home to play, undoubtedly blowing a sigh of relief to retreat back to La Sarthe's long straights and to rules that shamelessly favored their alternative diesel approach.*
At around this same time, the recession was in full swing and sponsorship money started drying up. And many of those same LMP2 teams, who lobbied so hard to keep the status quo, didn't return to the series either in 2009. Again, I would have to check my facts, but I seem to remember some of them waffling until the last minute. We all get angry when the manufacturers disappear, claiming how they're only involved in racing as a marketing exercise, but Andretti and Penske proved to be sand-kicking playground bullies themselves who stomped off when the going got tough. Be it big automotive corporations or the smallest privateer, when it comes to racing, money speaks with the loudest voice.
Although there's been some great racing over the years, especially in the GT category, I think 2009 was really the beginning of the end for the ALMS and it sort of lead the way and opened the window for the merger.
* I don't necessary mean this as a slap at Audi either. They clearly weren't happy with rules that gave the LMP2 cars an unfair advantage, especially at certain tracks. Just as the LMP2 teams WERE quite thrilled with how things were panning out.