The Bradley is a good combat vehicle. It has an effective armor envelope and provides a range of firepower. For a conventional battlefield, you'd be hard pressed to find a better infantry combat vehicle. But, it's a maintenance hog, you can hear it a mile away and it's heavy for its size. I would imagine its also much more expensive to operate in comparison to a wheeled vehicle. The US Army can afford the Bradley, but I'm not sure many others can. That's part of the reason why so few armies are equipped with the Bradley. Another supporting issue is deployability. If you're going to buy it, you need lift assets to get it where the action is.
There's nothing wrong with the LAV family. You have a lot of flexibility there. It has good mobility and enough firepower to get most jobs done that the infantry needs. It's quiet, and doesn't make you a slave to the metal like the Bradley. But, I'll grant you the Bradley is definitely a great IFV/CFV. But, the reality is that the Bradley is old technology. Although there isn't a real follow-on system to replace it, the Bradley is outdated right now. It's classed as a "Legacy System."
Ideally, you should have a mix of wheeled and tracked infantry carriers. The key question you have to answer is, "What do we want to do with this combat system?" If you're planning on fighting on a heavy mechanized battlefield, than something like the Bradley is the ticket. But, if it's peace enforcement/peace keeping or force projection, than wheels may be a better choice. But, the budget dictates what you can afford to procure. When an army purchases anything, it has to consider everything from initial development costs, to life cycle rebuilds and spares to fuel costs over 20-25 years. Right now, the GDLS tank plant in Lima, Ohio is rebuilding old M1 hulls and turrets from the early 80s into brand new M1A2 tanks. Who else could afford that?