Why not? Many Mosins were never issued, good as new. They have very good, practical accuracy. My unmodified 91/30 shot 2MOA at 100 yards with Mil-surp 148gr light ball, with match gread maybe even better. With my trigger work, bedding and other things anyone would do on a custom rifle, I probably can get sub MOA quite easily. I would say unless going for a magnum round there is no practical reason to not choose milsurp. My milsurp M1917, .30-06 has a great trigger, smooth action and while plinking it seems to hit whatever I put in front of it, from glass coke bottles to watermelons, soon I will formally report on it.
Plus many milsurps have neat characteristics. The mauser series is stronger and safer than many contemporary designs and the CRF system is great.
Don't discount the K-31, a great straight pull which much surplus ammo is match grade and fairly inexpensive over factory ammo.
The .30-30 is rimmed, yet it remains a popular caliber, and retains many characteristics of other rimmed rounds, namely the 7.62x54r. Finns have successfully used Mosin actions many years for military and police work, and they make some of the finest rifles in the world.
Plus the custom market for Mosins is quite large. Stocks, peep sights, bolts, bedding kits, scope mounts. Only thing is barrels, but you can get a PK or UK59 barrel and have it modified for around the same price, plus you get a heavy barrel that was designed for many, many rounds.
Maybe you have had duds but the Mosin is an unknown gem, and one with great potential. It fits right between .308 and .30-06, and match grade ammo can be found or made at the same or less price as any other caliber.
And why go milsurp? People don't realize you can get great results from an old Mauser, Mosin, or even Enfield. You can customize them more economically, and generally when its all said and done I can see the milsurp path being somewhat cheaper, just need to now where to look, and be willing for patience.
Regarding the magazine, it protrudes no more than most stocks and I find it's latch convenient for fast unloading, compared to a mauser which needs a 8x57 IS cartridge to unload.