...If the transaction costs are a major hurdle in getting people to start using Ripple...Users won't want the transaction cost to fluctuate orders of magnitude overnight, but that goes for holders of any currency.
It is a very common misconception to view the marginal XRP costs of a transaction as important (right now transactions cost 10 XRP). The real cost is the cost of opening a new Ripple account, which is 200 XRP. This is orders of magnitude greater.
Transaction costs are not particularly relevant to average users. In fact, Ripple transaction costs are orders of magnitude less than even Bitcoin! I think it would really help clarify things if people just forgot about Ripple's transaction costs and focused on the bigger effect of how new accounts get funded with their 200 XRP allocation.
For the statements I made above transaction costs can be substituted with account opening costs -- whatever costs are a hurdle to new users will do. You're right though that there should be more focus on the amount of XRP that is required to fund an account (and is bound to that account ever after).