The AFL is considering 10 options for the structure of the 2012 season, which will be the first year Gold Coast and Greater Western Sydney both play in the competition.
The options include increasing the final eight to nine or 10 teams and extending the finals series from four to five weeks.
Malthouse, whose team featured in five weeks of finals last year following the drawn grand final and subsequent replay, said the current configuration of a top eight "rewarded mediocrity”, and an increase of teams playing on would reduce the competition's elite status.
"Another week thrown in and perhaps playing the 10th side in a 17 or 18-team competition, to me, you may as well throw them all in and just say, we'll go through 24 weeks and all have a hit at finals," he said on Thursday.
"It's got to be elite and you've got to strive for that final six or four, and it won't be four … or final eight even, with 18 teams.
"It puts a line there that says underneath there is more than 50 per cent. To me, 50 per cent clubs playing in the finals series … it might be good for your record and numbers but it doesn't make a lot of sense to me.
"If you're going to have a finals series, it's an elite competition and it's got to be played in an elite manner."
Malthouse said the idea of extending the finals series by another week was asking a lot of clubs and players.
"The only way that I can see it as a non-administrator, don't worry about the dollars or the TV rights or anything else, because all those things are taken into consideration when you start talking about eight or nine teams in finals," he said.
"Five weeks of finals … finals series are the most draining period of the year from week one to week four if you manage to get there."
The NAB Cup's future has also been questioned, with the AFL likely to retain it in some format for next year.
Malthouse said the Magpies - who will play Essendon in the grand final on Friday night - were supporters of the pre-season competition's concept and labelled the competitive hit-outs as "bonus games" where clubs could trial moves such as Leon Davis' shift to the backline.
"I'm sure [the AFL] will come up with something. It's a long way off to start worrying about it now," he said.
"I don't think they're going to let you go into round one cold. It might be two practice matches - I've got no idea and I don't particularly care at this stage.
"It's not an issue. We're worried about round one via the last round of the NAB Cup series, and we're not going to just ignore this last game.
"It's going to be something that's experimental for some players, to see whether or not they can handle the fact we're going to 18 [on the field], three [on the bench] and one [substitute] as opposed to 18 and four last year.
"Practice matches are practice matches, but these competitions are a bit more fierce. They're not round one but they're stepping in that right direction, so under those circumstances, these are bonus games."
Leon Davis is a $266,700 forward in the Toyota AFL Dream Team competition.
