They probably saw Terry's Wonderland 3D sell almost a million copies and decided that was the way to go this time around. With DQM it must be even cheaper with the reuse of engine and assets of TW3D. Wouldn't be surprised to see a Caravan Heart remake instead of a Joker 3 next.
I still think they should make a new Monsters game... as well as a new mainline DQ game for 3DS. The fanbase is clearly still there on the 3DS if they're buying DQ remakes en masse like this.
I'd say those are fairly good sales for DQM2, considering it's the 2nd DQM remake and third DQ remake. Hardware seems to be bad across the board. It's kind of surprising that DQM2 would cause a HW sales bump at all honestly considering there already was Terry's Wonderland and a DQ7 remake on the system. Seems like Puyo Puyo sold in-line with what previous titles have done, thanks to the 3DS version. All the rest of the versions sold fairly crappily (esp the PS3 version imo), although I think eventually they may get through most of the Vita and Wii U shipments. I think they won't get through the 150K they hoped to sell on PS3 however...
NSMBU:
Week 49, 2012 (12/3 - 12/9) - 163,528
Week 50, 2012 (12/10-12/16) - 71,011 / 234,539
Week 51, 2012 (12/17-12/23) - 77,749 / 312,288
Week 52, 2012 (12/24-12/30) - 57,103 / 369,392
Week 1, 2013 (12/31 - 1/6) - 50,319 / 419,710
Week 2, 2013 (1/7 - 1/13) - 12,400 / 432,110
Week 3, 2013 (1/14 - 1/20) - 9,598 / 441,708
Week 4, 2013 (1/21 - 1/27) - 6,883 / 448,591
Week 5, 2013 (1/28 - 2/3) - 6,338 / 454,929
Week 6, 2013 (2/4 - 2/10) - 5,857 / 460,786
Nintendo Land:
Week 49, 2012 (12/3 - 12/9) - 71,121
Week 50, 2012 (12/10-12/16) - 41,497 / 113,618
Week 51, 2012 (12/17-12/23) - 51,373 / 164,991
Week 52, 2012 (12/24-12/30) - 44,056 / 209,047
Week 1, 2013 (12/31 - 1/6) - 41,426 / 250,473
Week 2, 2013 (1/7 - 1/13) - 11,703 / 262,176
Week 3, 2013 (1/14 - 1/20) - 8,740 / 270,917
Week 4, 2013 (1/21 - 1/27) - 5,914 / 276,831
Week 5, 2013 (1/28 - 2/3) - 5,161 / 281,992
Week 6, 2013 (2/4 - 2/10) - 4,486 / 286,478
Super Mario 3D World:
Week 47, 2013 (11/18-11/24) - 99,588
Week 48, 2013 (11/25-12/01) - 39,812 / 139,400
Week 49, 2013 (12/02-12/08) - 43,844 / 183,245
Week 50, 2013 (12/09-12/15) - 57,862 / 241,107
Week 51, 2013 (12/16-12/22) - 86,408 / 327,514
Week 52, 2013 (12/23-/12/30) - 64.573 / 392.087
Week 1, 2014 (12/31-1/5) - 60.397 / 470.438
Week 2, 2014 (1/6-1/12) - 14,584 / 485.022
Week 3, 2014 (1/13-1/19) - 11.694 / 496.716
Week 4, 2014 (1/20-1/26) - 10.128 / 506.844
Week 5, 2014 (1/27-2/2) - 8.288 / 515.132
Week 6, 2014 (2/3-2/9) - 5.448 / 520.580
Well at least 3D World held a similar kind of trend to NSMBU and I think generally did better in the new year than NSMBU did. Oh well, I think we'll slowly see it fall off the Famitsu charts as well, partly b/c of DKC.