Oh no - dont be sorry. I know for a fact that they is money to be made in MP. Just abandon SP and go head to head with Destiny. Halo, Call of Duty, Battlefiled, etc. I would love to see Mass Effect MP having millions of players and since MP is so profitable, why reinvest into SP? That is plain silly. 
But wait... why MP at all? Cost of development is high, there is maintenance cost and return is relatively lousy compared to mobile games. Reinvest money made from mobile games to MP? That again would be silly
- better reinvest into pachinko machines like Konami.
The current state of the gaming industry is in flux, as video game developers see more profits from digital income over the standard physical. With the recent announced information of Halo 5 making 500,000 in a week's time off of microtransactions alone, it doesn't go unnoticed. Also, take into account, that Halo 5 is only on a single platform.
While I do not think that single player campaigns should be abandoned, game developers are starting to realize, that while they might enjoy making a video game, with complex characters, choices, different worlds and compelling stories, once a player has completed the game, what else is there for them to do, aside from replaying it, only differently?
This is where single player DLC comes into focus. As most developers still want to share more stories with the players and fans, all while making profit to invest into the next iteration or more DLC. But you can only have so much single player DLC, so now comes your complete and game of the year editions. They signify the true end of everything. No more profits can be made after these copies are sold. Albeit sales, and newcomers to the game would amount to more profit, but they are far and few, and would take up the lion's share of income in comparison to long time fans, and those already fully invested.
Now comes multiplayer.
With multiplayer, there are no limits (aside from online connectivity and server functionality). A gamer's experience is their story. Their accomplishments, defeats, enemy encounters and close calls. They amount to more gameplay, with high replay value based on random online interactions with real life players. And with multiplayer, I think, that the developer is more free to create content over stories. No need to create a multitude of voice overs, or have to worry about developing more stories (which in turn frees up the writing team to work on new projects). Content. That is the main focus.
And with content, developers are free to create as much as they'd like, all while creating a continuous stream of unlimited income. But, I think, you shouldn’t be punished for not paying and grinding for in game currency to obtain what you want to or need. It should be fair and balanced. If players feel like they are being cheated, the income will reflect it, and the developer will be forced to adjust. Maybe not in that current game, but in the one that follows it.
I'll end with this, for as much as I enjoy Mass Effect, and there are literally no words to express my passion for the franchise, I have experienced, one of the most addictive and rewarding games of all time, that is Galaxy At War. If BioWare stopped multiplayer and only focused on single player, I would of course still respect and support them, but I would be utterly devastated. I would end up playing Galaxy At War until the servers were no more.