I wouldn't call older houses more risky, because newer houses have their own risks. The risks are just different. When we were looking to buy a house several years ago, I ruled out anything built after 2000 because of those risks.
Siding: Many of the alternatives to cedar siding simply do not hold up well. They need just as much maintenance as cedar, but if they don't get it they require expensive replacement siding. An older house with cedar siding which has been well maintained may very well be the best product you could hope for.
Electrical: This is probably the one area where a new house has a clear advantage. Outlet spacing, grounding wires, number of circuits, and the ability of the insulating covers to withstand heat have all improved over the years. Then there are the defective products of the past, such as Zinsco and Federal Pacific breaker panels. On the bright side, I think we're finally getting to the point where our houses' electrical demand is decreasing, so it's less likely the number of circuits will be inadequate going forward.
Plumbing: Here older may likely be better in that older may be more likely to be copper. All the other materials, older or newer, may be problematic in some way, or at least inferior.
Insulation: This can also be a concern, but for most houses the ceilings and floors can be easily upgraded. Upgrading walls can be more problematic.
Prior Upgrades: This is an area that you have to take on a case by case basis. As a general rule, remodeling that changes the floor plan is a negative, because the design is poorly thought out or simply doesn't fit. I've seen notable exceptions, however. Then there is also the un-permitted work which is done, but covered up (e.g. sheet rock) so that the quality of the work cannot be determined.
Bottom line is I wouldn't shy away from older homes. The one I ended up buying was built in 1969.