I wouldn't say developers are lazy, 90% of the time it's the publishers forcing the devs hand. But at the same time not every game made makes it's development costs back so at some point you either have to ship it and hope to reclaim what you can or suffer even more losses.
Also consider that in the old SNES days a game took a team of about 8 people to make and cost only a few hundred thousand over a 6 to 9 month development period. Nowadays you have that many people working on just the audio: voicing, sound effects, 5.1 surround musical score and so on - and the whole game costs millions with teams of up to 50+ people and development times of 2+ years.
Grand Theft Auto IV took over 1000 people and more than three and a half years to complete, with a total cost estimated at approximately $100 million.
No, developers aren't lazy, they're tired and stressed.