That is one of the main reasons that priority, and SR4 build points, both use flat costs for areas that have exponential costs after character creation. If some options are not cheaper to get at character creation, it is less likely those options will be taken at all. The downside, at least for some people, is that this subtly encourages further "front-loading" - taking a skill of 6 rather than two skills of 3, even if the latter would fit the concept better, for example.