Ask yourself this: Why do DDO points (or any other company or game specific currencies) exist?
Why have players buy points with cash to then buy items for points? Doesn't that seem inefficient and unnecessarily cumbersome? It's because they don't want you to know how much things really cost. Double bonus points further confuse the issue and separate your understanding of what 1445 DDO points really means.
1445 DDO points can mean anywhere from $18.64 (if you bought the $19.99 point bundle of 1550 points) to $8.76 (if you bought 33,000 points for $199.99 during a double bonus).
That's a pretty large swing in actual price. It's also very punitive to impulse buyers who only want to spend just enough to afford the item they want at the time and no more until the next time they want something. The difference between someone who buys XP pots as needed vs someone who buys chunks of points during a bonus at the start of the year and then buys XP pots when they're 20% off can be as high as a 266% difference.
The bottom line is that the way points are set up is to incent you to spend as much as you can all at once, in excess of what you currently want to spend so that you have a stockpile of points ready for when the things you want to spend points on (QoL things, content packs, pots, etc) go on sale.
I agree with the previous posters that double bonus points all the time would just establish a "new normal", while also watering down SSG's margins on impulse purchases and purchases by new players who don't yet know whether or not it makes sense to stockpile points given they may not keep playing the game.