As far as I know, the BioWare points system was discontinued years ago. To what extent it is still used I couldn't say, but I had the impression it was phased out by making the points themselves unavailable for purchase.
As far as I am aware, all of the DLC is available via traditional transactions for all systems. I think you'll have to cite a specific example of how you are attempting to purchase them and being unable to do so without BioWare points for anyone to figure out what is preventing you.
As far as the price, it is a bit of an irony that digital prices are consistently higher for longer, considering the medium is by orders of magnitude less expensive, in terms of distribution costs, when compared to traditional disc and cartridge games. I would compare it to phone companies who charged more for people transitioning to touch tone from pulse, when touch tone was by orders of magnitude less expensive for the phone companies to use. In this instance, a very small number of companies control digital distribution, and thus the prices will be artificially inflated due to the lack of competition. In the world of discs and cartridges, that level of control is much more difficult (especially because as a "physical medium" it is more regulated, especially when it comes to vertical integration.)
Long story short: Digital prices won't be coming down any time soon, and are likely to increase in the near future. Along with that, older DLC will maintain its price for longer than one would normally expect. The practice helps make up for shortfalls in other areas - such as the inability to charge more for games themselves (games went up in price last year for the first time in over 5 years.)